Physics

MTN Learn
Physical Sciences
Grade 12

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

CONTENTS Introduction ................................................................................................................ 3 Broadcast Schedules ................................................................................................ 5 Preparing for Examinations ...................................................................................... 6 Exam Techniques ....................................................................................................... 7 Exam Overview .......................................................................................................... 8 Prelim Preparation ..................................................................................................... 9 Spring School .............................................................................................................. 55 Prelim Review............................................................................................................ 69 Exam Revision: Paper 1 (Physics) ......................................................................... 71 Exam Revision: Paper 2 (Chemistry) ..................................................................... 77 Listener’s Feedback Competition .......................................................................... 83

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

INTRODUCTION
Have you heard about Mindset? Mindset Network, a South African non-profit organisation, was founded in 2002. Through our Mindset Learn programme, we develop and distribute high quality curriculum aligned educational resources for Grade 10 - 12. We make these materials available on TV (Dstv and Toptv channels 319), the Internet (www.mindset.co.za/learn) and as DVDs and books. At Mindset we are committed to helping South African learners succeed. This is why Mindset Learn is proud to offer Mindset Learn Xtra especially for Grade 10 – 12 learners. Learn Xtra offers you hundreds of hours of video and print support, live television shows between 4pm and 7pm every Monday to Thursday and a free Helpdesk where our expert teachers are on standby to help you. You can find out more about Mindset Learn Xtra at www.learnxtra.co.za. Learn Xtra also offers specific exam revision support. Every year we run Winter, Spring, Exam and Supplementary Schools to help you ace your exams. And now, Mindset is proud to announce a powerful partnership with MTN and the Department of Basic Education to bring you Mindset Learn Xtra Radio Revision powered by MTN – a full 3 months of radio programmes dedicated to supporting Grade 10 and 12 Mathematics, Physical Sciences and English First Additional Language.

Participating Community Radio Stations
Listen to any of the following community radio stations to get your daily dose of expert tuition and exam preparation. Also listen out for on air competitions in which you can stand a chance of winning great prizes. 1. KZN: a. Hindvani Radio b. Maputaland Radio 2. Limpopo: a. Sekgosese Radio b. Greater Tzaneen Radio c. Mohodi FM d. Moletsi e. Univen 3. Eastern Cape: a. Vukani fm b. Fort Hare Community Radio c. Mdantsane fm d. Nkqubela fm e. Graaff Reinet 91.5 fm (Durban) 102.3 fm ( rest of KZN) 170.6 fm 100.3 fm 104.8 fm 98.8 fm 98.6 fm 99.8 fm 90.6 - 99.9 fm 88.2 fm 89.5 fm 97.0 fm 90.2 fm

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Getting the most from Mindset Learn Xtra Radio Revision
The Grade 12 Physical Sciences we will focus on questions that come from recent previous exam papers. Please ask you teachers for copies of the exam papers or download the question papers and memos from our website or www.education.gov.za This booklet contains diagrams taken from the exam papers so that you will be able to follow what is said during the broadcast. Before you listen to the show, read through the questions for the show and try to answer them without looking up the solutions. If you have a problem and can’t answer the question, don’t panic. Make a note of any questions you have. When listening to the show, compare your approach to the teacher’s. Don’t just copy the answers down but take note of the method used. Make sure you keep this booklet. You can re-do the questions you did not get totally correct and mark your own work. Remember that exam preparation also requires motivation and discipline, so try to stay positive, even when the work appears to be difficult. Every little bit of studying, revision and exam practice will pay off. You might benefit from working with a friend or a small study group as long as everyone is as committed as you are. Mindset believes that Mindset Learn Xtra Radio Revision will help you achieve the results you want. If you find Mindset Learn Xtra Radio Revision a useful way to revise and prepare for your exams, remember that we will be running the following other great Learn Xtra Exam Revision programmes on Dstv and Toptv channels 319 during rest of 2012:   Grade 12 Mindset Learn Xtra Spring School: 1st October to 5th October Grade 11 and 12 Mindset Learn Xtra Exam School: 22nd October – 20th November

Both Spring School and Exam School will cover Mathematics, Physical Sciences, Life Sciences, Mathematical Literacy, English 1st Additional Language, Accounting and Geography.

Contact us
We want to hear from you. So let us have your specific questions or just tell us what you think through any of the following: LearnXtra @learnxtra [e-mail] 086 105 8262 Mindset Get the free app at pepclub.mobi

www.learnxtra.co.za

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

BROADCAST SCHEDULE
PRELIM PREPARATION Date 27-Aug 28-Aug 29-Aug 30-Aug 02-Sep 03-Sep 04-Sep 05-Sep 06-Sep 09-Sep Date 01-Oct 02-Oct 03-Oct 04-Oct 05-Oct 07-Oct PRELIM REVIEW Date 08-Oct 09-Oct 10-Oct 11-Oct 14-Oct EXAM SCHOOL Date 23-Oct 23-Oct 24-Oct 24-Oct 26-Oct 26-Oct 28-Oct 28-Oct Time 17:00 -18:00 18:00 -19:00 17:00 -18:00 18:00 -19:00 17:00 -18:00 18:00 -19:00 17:00 -18:00 18:00 -19:00 Topic
Motion, and Doppler Effect Momentum and Work Energy & Power Electricity Electromagnetism Organic Molecules & Properties Organic Reactions Rates & Chemical Equilibrium Electrochemistry & Chemical Industries

Time 18:00 -19:00 18:00 -19:00 18:00 -19:00 18:00 -19:00 17:00 -18:00 18:00 -19:00 18:00 -19:00 18:00 -19:00 18:00 -19:00 17:00 -18:00

Topic
Vertical Projectile Motion Momentum & Doppler Effect Work Energy Power Electrostatics, Capacitors & Electric Circuits Electrodynamics & Electromagnetic Radiation Organic Molecules Organic Reactions Rates of Chemical Reactions Chemical Equilibrium Electrochemistry & Chemical Industries

SPRING SCHOOL Time 10:00 -11:00 10:00 -11:00 10:00 -11:00 10:00 -11:00 10:00 -11:00 17:00 -18:00 Time 18:00 -19:00 18:00 -19:00 18:00 -19:00 18:00 -19:00 17:00 -18:00 Topic
Mechanics Organic Chemistry Electricity Rates & Chemical Equilibrium Waves, Light & Sound Electrochemistry

Topic
Mechanics Organic Chemistry Electricity Rates & Chemical Equilibrium Chemical Industries

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

PREPARING FOR EXAMINATIONS
1. Prepare well in advance for all your papers and subjects. You need to start your planning for success in the final examination now. You cannot guarantee success if you only study the night before an exam. Write down the date of your prelim and final exam so that you can plan and structure a study time table for all your subjects. Set up a study time-table according to your prelim and final Grade 12 exam timetable and stick to your study schedule. If you study a small section every day, you will feel you have achieved something and you will not be as nervous by the time you have to go and write your first paper. Your study programme should be realistic. You need to spend no more than 2 hours per day on one topic. Do not try to fit too much into one session. When you cover small sections of work often, you will master them more quickly. The broadcast schedule may help you to make sure you have covered all the topics that are in the exam. When studying don’t just read through your notes or textbook. You need to be active by making summary checklists or mind maps. Highlight the important facts that you need to memorise. You may need to write out statements such as definitions and laws a few times to make sure you can remember these. Check yourself as often as you can. You may find it useful to say the definitions and laws out aloud.

2. 3.

4.

5.

6. Practise questions from previous examination papers. Follow these steps for using previous exam papers effectively: ● Take careful note of all instructions - these do not usually change. ● Try to answer the questions without looking at your notes or the solutions. ● Time yourself. You need to make sure that you complete a question in time. To work out the time you have, multiply the marks for a question by total time and then divide by the total number of marks. In most exams you need to work at a rate of about 1 mark per minute. ● Check your working against the memo. If you don’t understand the answer given, contact the Learn Xtra Help desk (email: [e-mail]) ● If you did not get the question right, try it again after a few days. 7. Preparing for and writing examinations is stressful. You need to try and stay healthy by making sure you maintain a healthy lifestyle. Here are some guidelines to follow: ● Eat regular small meals including breakfast. Include fruit, fresh vegetables, salad and protein in your diet. ● Drink lots of water while studying to prevent dehydration. ● Plan to exercise regularly. Do not sit for more than two hours without stretching or talking a short walk. ● Make sure you develop good sleeping habits. Do not try to work through the night before an exam. Plan to get at least 6 hours sleep every night.

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

EXAM TECHNIQUES
1. Make sure you have the correct equipment required for each subject. You need to have at least one spare pen and pencil. It is also a good idea to put new batteries in your calculator before you start your prelims or have a spare battery in your stationery bag. 2. Make sure you get to the exam venue early - don’t be late. 3. While waiting to go into the exam venue, don’t try to cram or do last minute revision. Try not to discuss the exam with your friends. This may just make you more nervous or confused. 4. Here are some tips as to what to do when you receive your question papers: Don’t panic, because you have prepared well.
●

●

● ●

● ● ● ●

●

You are always given reading time before you start writing. Use this time to take note of the instructions and to plan how you will answer the questions. You can answer questions in any order. Time management is crucial. You have to make sure that you answer all questions. Make notes on your question paper to plan the order for answering questions and the time you have allocated to each one. It is a good idea always to underline the key words of a question to make sure you answer it correctly. When you start answering your paper, it is important to read every question twice to make sure you understand what to do. Many marks are lost because learners misunderstand questions and then answer incorrectly. Look at the mark allocation. Make sure you do not give more detail than required. When you start writing make sure you number your answers exactly as they are in the questions. Think carefully before you start writing. It is better to write an answer once and do it correctly than to waste time rewriting answers. DO NOT use correction fluid (Tippex) because you may forget to write in the correct answer while you are waiting for the fluid to dry. Rather scratch out a wrong answer lightly with pencil or pen and rewrite the correct answer. Check your work. There is usually enough time to finish exam papers and it helps to look over your answers. You might just pick up a calculation, language or a spelling error. In Physical Sciences make sure that every answer has the correct units. For vector quantities (force, displacement, velocity, acceleration, momentum, impulse and electric field strength) make sure you include the direction as well.

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

EXAM OVERVIEW
STRUCTURE OF PHYSICAL SCIENCES EXAM PAPERS Section A
One word answers Multiple choice questions

(All topics)
5 marks 20 marks 125 marks

Section B (Long questions)

PHYSICAL SCIENCE PAPER 1: PHYSICS
Mechanics ● ● ● ● ●

TOTAL MARKS: 150

3 HOURS

Momentum in 1 D Grade 11 Impulse and change in momentum Vertical projectile motion Frames of reference Work, power and energy

±50 marks

Waves, Sound and Light ● Doppler effect ● 2D and 3D wave fronts Electricity and Magnetism ● Electrostatics Grade 11 ● Electric circuits Grade 11 ● Electrodynamics Grade 12 ● Electromagnetic radiation Grade 12 Matter and Materials ● Optical phenomena and properties of materials

±25 marks

±55 marks

±20 mark

PHYSICAL SCIENCE PAPER 2:
Matter and Materials ● Organic molecules

TOTAL MARKS: 150

3 HOURS
±50 marks ±75 marks

Chemical Change ● Energy and chemical change Grade 11 ● Rate and extent of reactions ● Electrochemical reactions Chemical Systems ● Chlor-alkali industry ● Fertiliser industry ● Batteries

±25 marks

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

RADIO BROADCAST prelim preparation sTUDY NOTES GRADE 12 PHYSICAL SCIENCES

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

PRELIM PREPARATION
ON AIR COMPETITION QUESTION FOR WEEK 1 (26 AUG – 2 SEPT)
Question Ball 1 is projected upwards with an initial velocity of y m.s-1. At the same time, ball 2 is projected upwards with double the velocity of ball 1. Ignore the effect of air resistance. Ball 1 reaches its maximum height after t seconds. How long after this will ball 2 reach its maximum height? A B C 0s ts 2t s

ON AIR COMPETITION QUESTION FOR WEEK 2 (26 AUG – 2 SEPT)
Question Nitric oxide (NO(g)) forms in internal combustion engines by the direct combination of nitrogen and oxygen according to the following reversible reaction: N2(g) + O2(g) ⇌ 2 NO(g) During an experiment, 1 mol of O2(g) and 1 mol of N2(g) were place in a 2 dm3 closed container at 300 K. After some time, chemical equilibrium was established and 0,2 mol of NO was found in the container. What is the value for the equilibrium constant (Kc) for the reaction at this temperature? A B C 0,20 0,06 0,05

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

27-AUG

18:00 -19:00

VERTICAL PROJECTILE MOTION

STUDY NOTES VERTICAL PROJECTILE MOTION 1.
What is Projectile Motion? A projectile is an object that is given an initial velocity by shooting or throwing etc., and once launched, the only force acting on it is the force due to gravity. In the absence of air resistance, the object is free falling with a constant (uniform) acceleration of 9,8 m.s-2 called gravitational acceleration (g). The direction of this acceleration is always downwards. 2. Important Facts Concerning Vertical Projectile Motion:

● ● ● ● ●

At the greatest height of the upward motion: vf = 0 m·s-1 a = g = 10 m·s-2 downwards The object will take the same time to reach its greatest height from point of upwards launch as the time taken to fall back to point of launch If the object is being released from rest or being dropped, its initial velocity is 0 m·s-1. If the object is being thrown upwards, it must start with a maximum velocity and as it moves up, the velocity decreases until it stops. When an object is thrown upwards, you can treat the motion as two parts (upwards and downwards) or as a single motion, but the acceleration must be constant throughout the time. The sign of the direction of motion must stay the same as well.

3.

The Effect of Air Resistance

● ● ● ● ● ●

In most exam questions you will be told to ignore the effects of air resistance. Air resistance is a frictional force that opposes motion. When an object is moving up, air resistance will act downwards. When an object is moving downwards, air resistance will act upwards. Terminal velocity is reached when the downward force of gravity and the upward force of air resistance are equal. At terminal velocity there is no net force acting in on the object and so the acceleration is zero and the object falls at a constant velocity.

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4.

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Solving Vertical Projectile Motion Problems To solve vertical projectile motion problem we use equations of motion and graphs of motion Equations of Motion: These are found on the information sheet and are used to describe and calculate the motion of an object that is moving in one direction with a constant acceleration. Method for Using Equations of Motion: Draw a diagram of the situation in the question and enter all the numerical values onto your diagram. STEP 2: Select a direction as positive and do not change the sign of the direction STEP 3: Identify which equation to use, i.e. identify the known and unknown quantities STEP 4: Substitute into the equation and solve STEP 5: Interpret the answer - for vector quantities, give the direction in words Graphs of Motion We use three different graphs. A. position – time graph. B. velocity – time graph acceleration – time graph C. Interpreting Graphs of Motion STEP 1:

● ● ● ● ● ●

Check the labels and units on the horizontal and vertical axes When the graph is above the horizontal axis, the position, velocity or acceleration is positive. Identify the direction of motion from the graph. The gradient of a position-time graph tells you about the velocity of the object and the gradient of a velocity-time graph tells you about the acceleration of the object. The area between the graph and the time axis on a velocity-time graph gives the change in position, and on an acceleration-time graph this area is the velocity. Use a ruler to read off values - start on the time axis and graph a vertical line till it touches the graph; then graph a horizontal line and read off the value on the vertical axis. Make sure you know what all three graphs of motion look like for the following situations: ○ an object dropped from a height above the ground ○ an object that is thrown up from the ground and falls back down again ○ a ball that is dropped from a height and bounces up off the ground

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Sketching Graphs of Motion ● ● ● ●

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

● ● ● ●

Select the position of the observer (usually represented as the origin) Make sure you label the axes with units Select a good scale for an accurate graph Learn the basic shape of each of the graphs for the following situations: ○ stationary object ○ constant velocity moving towards and away ○ constant acceleration moving towards and away Make sure you know when the velocity is zero Make sure you know when the velocity is increasing or decreasing Plot your points accurately After drawing the sketch check that the sketch describes the situation given

QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 2.3 and 3 Diagram for Question 2.3 (Nov 2011 P1)

Diagram for Question 3 (Nov 2011 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

28-AUG

18:00 -19:00

MOMENTUM & DOPPLER EFFECT

STUDY NOTES MOMENTUM
Definition: Momentum is a vector quantity and has the unit: kg·m·s-1. p = mv The Principle of Conservation of Linear Momentum The total linear momentum of an isolated system remains constant in magnitude and direction. Impulse Definition: Impulse is the change in momentum of a body ( Impulse and Newton’s 2nd Law Newton’s 2nd Law states that the net force exerted on an object is directly proportional to the rate of change of momentum in the direction of the force net. Equation: Fnet = m v÷ t Fnet . N.s t =m v p =m v =m(vf –vi)

Equation for Impulse: Units for Impulse:

Collisions There are a number of different possible collisions that can take place between two objects moving along the same line (one dimension): ● one moving object collides with a stationary object ● two objects move towards each other ● two objects pushed together and kept stationary. When they are released they move apart (explosion) Possible results ○ one object moves and the other object stops moving ○ the two objects join together and move off at the same speed ○ both objects move but are not joined We classify collisions as either elastic or inelastic. ● In an elastic collision kinetic energy and momentum are conserved. ● In an inelastic collision, momentum is conserved, but not kinetic energy. The conservation of kinetic energy is determined by calculating the total kinetic energy of all parts of the closed system before the collision and comparing that to the total kinetic energy of all the parts of the closed system after the collision.

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DOPPLER EFFECT

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Definition: The Doppler Effect occurs when the frequency of waves produced by a source is observed to be higher or lower than the actual frequency of the source.

● The Doppler Effect can be observer using water waves, sound waves or light.
Facts about The Doppler Effect you must learn ● ● ● ● ● ● There must be relative motion between the source of waves and the observer. For Grade 12 examinations, one object will be stationary The most common example of the Doppler Effect is for sound waves For sound waves: ○ Increasing the frequency means the pitch increases ○ Decreasing the frequency means the pitch decreases When the observer moves towards the source or the source moves towards the observer, the frequency increases When the observer moves away from the source or the source moves away from the observer, the frequency decreases

The Doppler Effect Equation
L

v v v v

fL = frequency of the listener fs = frequency of the source vL = speed of the listener vL = speed of the source v = speed of sound in the given medium Although the equation looks complicated, it simply describes the relationship between the frequency of the listener and frequency of the source. The part in brackets is a ratio of the velocities and can either be:  a number bigger than 1 (source or listener are moving towards each other)  equal to one  a number smaller than 1 (source or listener are moving away from each other)

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Using the Doppler Effect Equation 1. 2. Write down the formula with the ± signs.

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

There are two methods to decide on the sign: Method A Define the direction from the listener (L) towards the source (s) as positive (+). Substitute the values of the unknown velocities with this sign convention and thus replace the ± sign in the equation. Method B If either the source or listener is moving towards the other, then the frequency of the listener (fL) must be greater than the frequency of the source (f s). This means that in the ratio of velocities, the numerator must be bigger than the numerator. Select the plus sign to increase the numerator and the minus sign to decrease the denominator so the equation becomes: v v L vv If either the source or listener is moving away from the other, then the frequency of the listener (fL) must be smaller than the frequency of the source (f s). This means that in the ratio of velocities, the numerator must be smaller than the numerator. Select the minus sign to decrease the numerator and the plus sign to increase the denominator so the equation becomes: vv L v v

3. 4. 5.

Substitute zero values for the velocity of the source or the observer into the equation. Substitute the speed of sound given in the question or use: Speed of sound in air = 340m.s-1 Solve for the unknown.

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

QUESTIONS FOR DISCUSSION:
Nov 2011 P1 Question 2.1 and 4 Nov 2011 P1 Question 6 Diagram for Question 4.1 - 4.2 (Nov 2011)

Diagram for Question 4.3 - 4.4 (Nov 2011)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

29-AUG

18:00 -19:00

WORK ENERGY POWER

STUDY NOTES WORK
Definition: Work done is energy transferred and it is measured in the unit of Joules. Work is not a vector but a scalar quantity. We don’t indicate direction for work. Equation for Calculating Work W = F·Δx∙cosθ    When the force and change in position are in the same direction, the angle between these vectors is 00. Since cosθ = 1, the work done is a maximum. When the force and change in position are in the opposite direction, the angle between these vectors is 1800. This gives a negative answer for the work done as the force will be a frictional force. When the force and change in position are at 900 to each other (perpendicular), no work is done (cos900 = 0).

ENERGY

Energy is also a scalar quantity. Energy is the ability to do work and is also measured in Joules Kinetic energy is the energy as a result of movement K = Ek = ½ mv2 Gravitational Potential Energy is the energy possessed as a result of position U =Ep = mgh Mechanical Energy is a combination of kinetic and potential energies. Mechanical Energy = Potential Energy + Kinetic Energy Emech = U + K = Ep + Ek Law of Conservation of Energy Energy cannot be created nor destroyed. Energy can only be converted from one form to another. During free fall, mechanical energy is conserved Emech (initial) = Emech (final) Friction is a non-conservative force and where friction is present, mechanical energy is not conserved. The energy “lost” is due to the work done by the frictional force and may be converted into heat, sound, electrical energy or even light.

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WORK- ENERGY THEOREM

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

The work done by a constant net force in displacing an object is equal to the change in kinetic energy of the object. Wnet = ∆Ek = F∆x.cosθ

POWER
Power is also a scalar quantity. It is measured in the unit of Watts. Power = work done ÷ time = energy transferred ÷ time When a machine causes an object to move at constant velocity we can calculate the power of the machine by using the equation: P = F.v

QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 2.2 and 5 Diagram for Question 2.2 (Nov 2011 P1)

Diagram for Question 5 (Nov 2011 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

30-AUG 18:00-19:00
STUDY NOTES ELECTROSTATICS

ELECTROSTATICS, CAPACITORS & ELECTRIC CIRCUITS

You must revise the following topics from Grade 11: Electric Fields   An electric field is a region in space in which an electric charge will experience a force represented by a pattern of field lines. Check that you can draw and interpret the electric field pattern for different point charges and between parallel plates.

Conservation of Charge The Law of Conservation of Charge states that charges cannot be created nor destroyed but are merely transferred from one object to another, i.e. the amount of charges in a closed system remains the same. Use the equation below to calculate the charge on two spheres that are brought into contact and then separated: Qnew = (QA+QB) ÷ 2 Coulomb’s Law of Electrostatics The Coulomb’s Law states that the force of attraction or repulsion between the two electric charges at rest is directly proportional to the product of the charges, and inversely proportional to the square of the distance between them. F = KQ1Q2 r2 Q = charge, unit: coulomb (C) r = distance between the charges, measured in m

k = Coulomb’s constant = 9 x 109 N·m2·C-2 Electric Field Strength Electric field strength is the force per unit charge which a positive charge will experience at that point Equation when using a point charge: E=F q Units: Force – Newton (N), Charge – coulomb (C), Field Strength – N.C-1

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Electric Field Strength around a large charged sphere (Q) The electric field strength at a distance from charge Q is given by the equation. E = kQ r2 Electrical Potential Difference   A charge placed at any point in an electric field possesses potential energy. The potential energy in an electric field is defined as the work it takes to move a unit positive charge from the point at lower potential to the point at higher potential. V=W Q Units: V – volts (v), W – joule (J) Electric Field Strength between two charged parallel plates   The electric field strength between 2 oppositely charged parallel plates is uniform, i.e. a charge placed anywhere between these plates will have a constant force acting on it. The electric field strength between the plates is calculated using the equation E = V÷d where d is the distance between the plates in m, and V is the potential difference measured in volts

CAPACITORS
    A capacitor is a device that can store energy. Inside a capacitor the terminals connect to two metal plates that are separated by an insulating material called a dielectric. The dielectric can be anything that does not conduct electricity readily and it keeps the plates from touching each other. The bigger the area of the plates, the more charge the capacitor can store. Symbol:

Four factors affect the ability of the capacitor to store electrical charge. These are o The potential difference between the plates o The area of the plates o The distance between the plates o The insulating substance between the parallel plates.

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Capacitance  

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Capacitance is a measure of the ability of a capacitor to store charge. The capacitance (C) of a capacitor is the charge stored on its plates per volt of potential difference between the plates. C = Q÷V The units for capacitance is coulomb per volt (C.V-1) called a farad (F). The farad is a very large unit. Typical capacitor are in o Microfarads, μF = 10-6F o Nanofarads, nF = 10-9F o Picofarads, pF = 10-12F

 

ELECTRIC CIRCUITS
Resistance and Ohm’s Law Ohm’s Law states that the current between any two points in a conductor is directly proportional to the potential difference between these points provided that the temperature of the conductor remains constant. Equation: R=V I

Units : current – amperes (A), voltage – volts (V) and resistance – ohms (Ω)  The resistance of the conductor depends on o o o o The type of material used The length of the conductor – the longer the conductor, the greater the resistance The thickness of the conductor – the thicker the conductor, the smaller the resistance The temperature of the conductor – the higher the temperature, the greater the resistance

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Series and Parallel Connections
Components Resistors Connection Series Diagram

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Current (A) The current in a given series circuit is the same throughout the circuit. The more resistors in series, the greater the resistance; the current decreases.

Potential Difference (V) Resistors in series are potential dividers, i.e. VT = V1 + V2

VT A
V1 V2

RT = R1 + R2

R1

R2

Resistors

Parallel 1 1 RT R2 = 1 R1
A1

+

VT
AT
V1

Resistors in parallel in a given circuit split the current. AT = A1 + A2 (the more resistors in parallel, the greater the total current because the total resistance decreases.)

R2

Resistors in parallel have the same potential (in the absence of another resistor in series).

A2

R1
V2

VT = V1 = V2

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

EMF and Internal Resistance  The emf of a cell is the maximum amount of energy which the cell can supply.  We measure the emf of a cell or battery by connecting a voltmeter across the terminals. The battery may be connected to an open circuit  When the cell is delivering current to a circuit (closed circuit), the terminal potential difference is less than the emf; the difference is called ‘lost volts’ or internal volts.  The reason there is a difference between the emf and potential difference across the terminals of a battery in a closed circuit, is that there is an internal resistance inside each cell. Equation emf = terminal potential difference + “lost volts” Emf = IR + Ir Emf = I(R + r) Energy in an Electric Circuit Potential difference in an electric field  Potential difference V = W ÷Q Quantity of charge: Q = I ∆t  Work done by an electric field: W = V I ∆t

Power: the rate at which work is done Power = work Time Units: watt (W) Electrical Power: P = V I or P = I2R or P= V2 ÷ R

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QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 8, 9 and 10 Diagrams for Question 8 (Nov 2011 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagrams for Question 8 (Nov 2011 P1)

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Diagrams for Question 10 (Nov 2011 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

02-SEP 17:00 -18:00
STUDY NOTES ELECTRODYNAMICS

ELECTRODYNAMICS & ELECTROMAGNETIC RADIATION

There are two electrical machines that you need to know about:   The Electric Motor (Supply electrical energy  produce mechanical energy) The Electric Generator (Supply mechanical energy  produce electrical energy)

The Electric Motor In an electric motor, an electric current passes through a coil in a magnetic field. The combination of the two force fields produces a torque (rotation) which turns the coil of the motor. The split ring commutator reverses the current each half turn to keep the coil turning in the same direction. The brushes on the commutator allow for the free rotation of the coil. If we want to maximise the force created by the motor effect we can:    Make the current stronger Increase the strength of the magnetic field Make sure that the angle between the magnetic field direction and the direction of the current is as close to 90º as possible, since the maximum effect is when the current flows at 90º to the magnetic field lines.

The Electric Generator (Dynamo) The generator illustrates the principle of electromagnetic induction. Faraday’s Law of Induction The induced emf in a conductor is directly proportional to the rate of change of the magnetic flux through the conductor. There are two types of generators: A DC generator: Same structure as a motor but the coil is turned and produces Direct Current (D>C). This machine has a split ring commutator. An AC Generator (Dynamo): This machine has slip rings and produces alternating current

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Alternating Current

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Our power stations produce alternating current and the current that we get from the plug points in our homes is AC. The frequency of alternating current in South Africa is 50Hz. The graph below shows how the current changes direction every half revolution, and is changing strength continually as the coil rotates in the magnetic field.

Advantages of AC We can use transformers to step up the voltage and step down the current. This enables the distribution of electricity on the national power grid with low energy loss. Calculations for AC The potential difference varies between 0V and 311V. This has the same effect as a constant value of 220V. We call this the root mean square voltage

The current also fluctuates with time:

The average power in an AC circuit is calculated by using: Pave = VRMS IRMS Pave = I2RMSR Pave = V2RMS ÷ R

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ELECTROMAGNETIC WAVES

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Source: http://www.warren-wilson.edu Electromagnetic waves can be set up by charges that oscillate backwards and forwards. The oscillation causes a vibration which in turn causes a wave shaped electric field. As the electric field changes, it induces (creates) a changing magnetic field at right angles to it. As the magnetic field changes, it induces a changing electric field at right angles to it. It this way the wave self propagates (keeps on going). The magnetic and electric fields are in phase with one another. Electromagnetic waves are transverse waves. Electromagnetic waves do not need a physical medium to travel in. They can travel through a vacuum. All electromagnetic waves travel at a speed c = 3 X 108 m.s-1 (in a vacuum) v=c=fxλ

THE ELECTROMAGNETIC SPECTRUM
There are different types of electromagnetic waves which we arrange in order of increasing frequency in spectrum: Radio waves, Microwaves, Infra-red, Visible Light, Ultra-violet light, X-rays, Gamma Rays.

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PROPERTIES OF LIGHT SPECTRA

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

There are three types of spectra you need to be able to explain:  Visible spectrum When visible white light is refracted through a prism, we see the colour of the different frequencies of light (colours of the rainbow).  Line emission spectrum When energy is given to any element in its gas phase, it will radiate light of certain frequencies. When this light is refracted through a prism, a unique pattern of lines appears for each element. These lines correspond to the energy levels of electrons in the atoms that have been excited.  Line absorption spectra A line absorption spectrum is formed when white light is passed through a cold gas (element) and then passed through a prism. We see a continuous spectrum but with a unique pattern of black lines. The black lines represent frequencies of light that have been absorbed by the gas. Diffraction of Light When light of a single frequency passes through a small slit, a diffraction pattern will form as shown below:

Source: Wikipedia - Diffraction

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Equation for Calculating the Angle of Diffraction, θ sin  

m a

θ = angle of diffraction (between the normal to the slit and the dark fringes). d = width of slit (m). λ = wavelength of light (m). m = the number (+1, +2, +3 etc) of the dark band from the centre of the diffraction pattern. Young’s Double Slit Experiment When light of the same frequency (colour) passes through two narrow slits close to each other, a pattern of evenly spaced bright and darker bands can be projected onto a screen. The bright bands are formed as a result of constructive interference, while the darker bands are a result of destructive interference. This experiment confirms that light has wave properties. Interference: The Principle of Superposition The magnitude of the resultant displacement is the algebraic sum of the displacements of the pulses before interference occurs. In other words: When two waves meet, they interact with one another.    When two peaks meet, they make a larger peak equal in amplitude to the size of the sum of the amplitudes of the original two waves. This is constructive interference or an anti-node. When two troughs meet, they make a larger trough equal in amplitude to the size of the sum of the amplitudes of the original two waves. This is constructive interference or an anti-node. When a peak and a trough meet, they make a smaller peak or trough equal in amplitude to the size of the difference between the amplitudes of the original two waves. This is destructive interference or a node.

Photoelectric Effect When light of high enough energy collides with an electron near the surface of a metal, it transfers all its energy to the electron. If the electron gains enough energy, it is knocked off the metal surface. Wave theory relates the energy of the wave to amplitude (intensity / loudness). Increasing the brightness of a red light does not knock off electrons from the surface of a metal but a dim ultraviolet light does. Wave theory of light cannot explain this result. Planck suggested that energy was quantised and depended on frequency. Einstein applied Planck’s ideas to light and proposed that light consists of particles called photons. The energy of the photon (a packet of energy) is given by the equation: E= hf h = Plank’s constant (6,6x10- J·s)
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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Different metal surfaces require different amounts of energy to release an electron. The minimum amount of energy required is called the work function of the metal (W 0) and this corresponds to the threshold frequency of the photon (f0). When the energy of the photon is greater than the work function, the electrons knocked off the surface of the metal gain kinetic energy too. Hence the equation for the photoelectric effect is: E = h.f= W0 + Ek = h.f0 + ½ m v2 Increasing the brightness (intensity) of a source of light increases the number of photons released and will increase the number of electrons knocked off if the photons have enough energy. The photoelectric effect gives evidence that the light has a particle nature. Duality of Light Light has both a wave nature and a particle nature at the same time. De Broglie’s Wave Equation Based on the duality of light, de Brogile suggested that all particles behave as waves do. It has been shown that very small particles, such as electrons and neutrons, form an interference pattern similar to X-rays. For bigger particles like a tennis ball, the wavelengths are very small and effectively meaningless.

λ – de Broglie’s wavelength (m) m – mass of particle (kg)

h – Plank’s constant (6,6x10- J·s) v – velocity of particle (m·s- )
1

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QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 11, 12, 7 Diagrams for Question 11 (Nov 2011 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagrams for Question 7 (Nov 2011 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

03-SEP

18:00 -19:00

ORGANIC MOLECULES

STUDY NOTES ORGANIC MOLECULES
Important features of Carbon • • • Carbon has a valency of 4 (can form 4 bonds), and has 4 valence electrons (outermost energy level). Carbon has the ability to form long chains with other C atoms – called catenation. Carbon has the ability to form rings by joining with other C atoms

Representations of Organic Molecules • • Molecular formula: Condensed formula: C6H13OH

CH3CH2CH2CH2CH2CH2OH

•

Structural formula:

HYDROCARBONS
They are molecules that contain only hydrogen and carbon atoms. There are an infinite number of different hydrocarbon molecules. Functional group: The special arrangement of atoms in part of a molecule that gives the molecule particular characteristics. Types of hydrocarbons • • Saturated – single bonds only (functional group) Unsaturated – double and triple bonds (functional group)

Homologous Series Family or group of molecules that have the same functional group and the same general formula. Alkanes • Single covalent bonds • SATURATED molecule. • General formula: CnH2n+2 Alkenes • have one or more C=C double bonds • The general formula: CnH2n. • UNSATURATED molecule

CH3 - CH2-CH2-CH3 butane CH2=CH-CH2-CH3 but-1-ene 34

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Alkynes • • • One or more triple bonds General formula: CnH2n-2 UNSATURATED molecule

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

CHC-CH2-CH3 but-1-yne Naming alkyl groups (side chains) Alkyl group structure CH3 CH CH 3 2 CH3CH2CH2 CH CH CH CH 3 2 2 2 Alkyl name methyl ethyl propyl butyl

RULES FOR NAMING ORGANIC COMPOUNDS (IUPAC RULES)
• • Identify the functional group of the molecule – this determines the ending of the name, e.g. all alkanes end in –ane. Find the longest continuous carbon chain and allocate its prefix according to the number of carbon atoms in the chain (see table for prefixes). Name prefixes No of C atoms 1 2 3 4 5 6 7 8 Prefix meth eth prop but pent hex hept oct -

• Number the carbon atoms in the chain. Number them so that the functional group is on the carbon of lowest possible number. Double and triple bonds take preference over side chains. • Name the branched group according to the number of carbon atoms it has, and give it a number according to the carbon atom to which it is attached.

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

• If there is more than one branched group of the same kind, use the Greek prefixes di, tri, tetra, penta and so on to indicate this. • If a halogen atom is attached to the carbon chain, it is treated as an alkyl group and then the prefixes: fluoro-, chloro-, bromo -, and iodo – are used. Alcohols • • • • • •

-O-H (hydroxyl) is the functional group. (Not called hydroxide OH-)
Named using the ending –ol. –O-H group gets the lowest possible number Alcohols are oxidised to carboxylic acids when treated with strong oxidising agents Alcohol molecules have a non-polar hydrocarbon end and a polar –O-H section Alcohols are solvents for polar and non-polar solutes Classification of alcohols depends on the number of carbons attached to the carbon bonded to the hydroxyl: Primary – only 1 carbon, Secondary ( 2 carbons) and Tertiary ( 3 carbons)

Carbolic Acids • Compounds that have the carboxyl, -COOH functional group • The ending -oic acid denotes that we are dealing with a carboxylic acid. • Are relatively weak acids. Esters

O

• These are compounds that have the C-O- C functional group. • Esters arise by the reaction between a carboxylic acid and an alcohol: • All esters consist of two parts in their name: o First part: an alkyl derived from the alcohol used, o Second part (separate word) ends in -anoate derived from a carboxylic acid (has the double bond O) Ketones • • Functional group: Carbonyl group (C=O) found in the middle of the molecule Suffix: -one ( pronounced own) Example: propanone The carbonyl group (C=O) is polar.

•

Aldehydes • • Functional group: Carbonyl group (C=O) found at the end of the molecule Suffix: -al Example: propanal

H

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ISOMERS

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Isomers are compounds which have the same molecular formula, but different structural formulae.

PHYSICAL PROPERTIES OF ORGANIC MOLECULES
Molecules are held together by intermolecular forces. In order to separate these molecules from each other requires energy. The stronger the intermolecular forces, the more energy that is required to separate or break these bonds. This will lead to a higher melting point, boiling point, etc. Boiling and Melting Points As the strength of the intermolecular forces increase, the boiling point and melting point will increase. Thus molecules where there are hydrogen bonds present will have a higher melting point and boiling point than those molecules where there are weaker London forces or Van der Waals forces present. Vapour Pressure Vapour pressure is the amount of pressure that the gaseous molecules exert above the surface of the liquid phase. The vapour pressure will decrease as the size of the molecule increases (chain length). Vapour pressure is an indication that there are weak intermolecular forces present in the liquid phase. Viscosity A liquid that has a low viscosity will be able to flow more easily. Thus, where hydrogen bonds are present, there will be a much higher degree of viscosity. The opposite is true for the weak Van der Waals forces. Viscosity will also increase as the length of the carbon chain increases. Density The density of organic molecules will increase as the length of the chain increases. Surface Area As the surface area of the molecule decreases, there will be lower boiling and melting points as the intermolecular forces will be weaker. Phases As the chain length increases, the melting and boiling points will increase. The smaller molecules will then be gases at room temperature and the longer chain lengths will be liquids or solids at room temperature

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QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 3 & 4 Diagrams for Question 3 (Nov 2011 P2)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagrams for Question 4 (Nov 2011 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

04-SEP

18:00 -19:00

ORGANIC REACTIONS

STUDY NOTES ORGANIC REACTIONS
Combustion reactions: • • • Hydrocarbons react with oxygen to form water and carbon dioxide and energy. Alkane example: Alkenes and Alkynes undergo similar reactions to form the same products.

Substitution reactions • • An atom or group of atoms in a molecule is substituted by another. One atom or group is removed and another takes its place. E.g.1 CH4(g) + Br2(g)  CH3Br(g) + HBr(g) E.g. 2 CH3Cl(g) + H2O(l)  CH3OH(aq) + HCl(aq) Addition reactions • • • • • Reverse of elimination reactions. The number of molecules decreases in addition reaction (on product side). High T favour elimination reactions and low T favour addition reactions. Therefore, we can drive reactions in opposite paths. Addition reactions generally occur faster than substitutions reactions. E.g. C H (g) + H O(l)  C H OH(g) 2 4 2 2 5 Elimination reactions • • • • Molecule of a reactant breaks up to form 2 or more new molecules Opposite of addition reactions. Number of molecules greater on product side. Single bond is ELIMINATED and double bond forms! Halogenation Hydration

E.g. 1 C2H5OH(g) + --(conc. acid + heat) C2H4(g) + H2O(l) + H+

Dehydration is the elimination of the hydroxyl (-OH) and the H atom from the alcohol. E.g. 2 C2H5Cl(aq) + NaOH(aq)  C2H4(g) + NaCl(aq) + H2O(l) Dehydrohalogenation is the elimination of the halogen atom (Cl) and an H atom leaving a carbon = carbon bond – strong base is used.

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Cracking • • Heating to a high temperature Produces unsaturated products E.g. CH CH  CH = CH + H 3 3 2 2 2 Oxidation • • •

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Alcohols for example can also undergo oxidation. Oxidation of a primary alcohol: K2Cr2O7 as catalyst – forms and aldehyde. Oxidation of a secondary alcohol: K2Cr2O7 as catalyst – forms a ketone.

QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 5 Diagrams for Question 5 (Nov 2011 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

05-SEP

18:00 -19:00

RATES OF CHEMICAL REACTIONS

STUDY NOTES ENERGY CHANGES DURING CHEMICAL REACTIONS
      Most reactions do not begin until an amount of energy (activation energy) has been added to the reaction mixture. The activation energy is often called the ‘energy hill’ which must be ‘overcome’ by the addition of this amount of energy before a reaction can take place. When activation energy is added to the reactants, a so-called activated complex is formed. Activated complex – temporary, unstable, high-energy composition of atoms, which represents a transition state between reactants and the products. When the activated complex is formed during a reaction, this complex can lead either to the formation of new bonds, i.e. molecules of the products, or to re-formation of the old bonds, thereby returning to being reactants. For the reaction AB + C  A + BC The formation of an activated complex as a transitional step can be represented as follows: AB + C  [ABC]  A + BC  The peak of the energy hill indicates the energy of the activated complex.  When an activated complex is formed during a reaction, this complex can lead either to the formation of new bonds, i.e. molecules of the products or to the re-formation of the old bonds, thereby returning to being the reactants. This is reversibility for the reaction.

HEAT OF REACTION (ENTHALPY)
 Heat of the reaction (∆H) is the difference between the energy of the products and the energy of the reactants. ∆H = Eproducts - Ereactants For an endothermic reaction, Eproducts > Ereactants, Therefore, ∆H is positive.



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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Activation Complex

POTENTIAL ENERGY

EReleased EA ΔH Reactants Products

Reaction co-ordinate Note: In a reversible reaction, the energy released in forming the products in the forward reaction is the same as the activation energy (EA) of the reverse reaction.  For an exothermic reaction, Eproducts < Ereactants, ∆H is negative. Activation Complex POTENTIAL ENERGY EA EReleased

Reactants

ΔH Products

Reaction co-ordinate

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The Mechanism of a Catalyst 

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

A catalyst mechanism: the function of a catalyst is to provide an alternate route for the reaction to take place. This route has a lower activation energy, and the rate of the reaction increases. A catalyst forms part of the activated complex and when this decomposes the catalyst is released, unchanged. Activation Complex POTENTIAL ENERGY

EA EA Reactants

EReleased

ΔH Products

Reaction co-ordinate     The function of a catalyst is to provide an alternate route for the reaction to take place. This route has a lower activation energy, and the rate of the reaction increases. A catalyst forms part of the activated complex and when this decomposes the catalyst is released, unchanged. Two kinds of catalysis: o Homogenous – catalyst is the same phase as the reactants. o Heterogeneous – catalyst in different phase as the reactants. Catalysts cannot cause a reaction to occur; they can only affect the rate of the reaction.

RATES – SPEED OF A REACTION
When we study the rate of the reaction, we study the speed at which the reaction occurs.

Macroscopic VS Microscopic
It is important to know that no one has ever seen an atom and it is very unlikely that anyone will see an atom in the near future. What we see in chemical reactions is known as MACROSCOPIC observations. What is actually happening to the atoms, we refer to as MICROSCOPIC changes. Often MICROSCOPIC changes are just THEORY.

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Collision Theory

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

A THEORY is our best explanation of what we observe right now. FACTS have been seen and are what science has proved to be correct.
COLLISION
Particle 1 Particle 2

We need to understand how atoms behave. If we had magic spectacles (glasses) and were able to see atoms moving around, we would notice the following:     Reactions take place when particles collide. Not all collisions lead to reactions. Those collisions that do lead to reactions are called effective collisions. To increase the rate of a reaction, the number of possible effective collisions should be increased.

In other words, the more often we can make atoms collide, the faster the reaction will take place. Factors that Influence Rate       Temperature – The faster the particles move, the more likely they are to collide, so the more likely they are to react. Pressure (only in gases) – The more you push the particles together, the more likely they are to collide, so the more likely they are to react. Concentration (solutions and gases) – the more particles squashed in per dm3, the more likely they are to collide, so the more likely they are to react. State of division and size of reaction surface (solids) – the more particles open to be reacted with, the more likely they are to collide, so the more likely they are to react. Catalyst – the activation energy is lowered for the reaction making it easier for substances to react, so they react faster. Nature of reacting substances – different types of substances, by their very nature, react at different speeds. For example, iron oxidises (rusts) relatively slowly while carbon (coal) oxidises (burns) fairly fast

Measuring Reaction Rate If we do an experiment to establish the speed (rate) of a reaction under different conditions, we can measure how fast the reaction is proceeding in a number of different ways:  how reactants disappear or products appear  colour changes (colour cards or spectrophotometers)  concentration of ions (conductivity)  gas volume produced  mass changes  volume of solid formed

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Catalysts  A catalyst is a substance that speeds up a chemical reaction without being chemically changed itself. It does not form part of the product.  Catalysts make it possible for reactants to enter a new transition state that has less potential energy. (Lower activation energy)  Catalysts provide a new MECHANISM for the reaction.  The reaction mechanism is the sequence of events at a molecular level that control the speed and outcome of a reaction. Types of Catalysts    Heterogeneous – usually solid with gas or liquid moving over it (motor vehicle catalytic converters) Homogeneous – usually all in the liquid phase Enzymes – very specific shaped biological molecules (lock and key mechanisms)

QUESTIONS FOR DISCUSSION:
Nov 2011 P2 Question 6 Diagrams for Question 6 (Nov 2011 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

06-SEP

18:00 -19:00

CHEMICAL EQUILIBRIUM

STUDY NOTES
What is Equilibrium?    Reactions that take place in both the forward and reverse directions simultaneously are called reversible reactions. Observable macroscopic changes stop, while microscopic changes continue as reactants change to products, and products change back into reactants. When the rate of the forward reaction equals the rate of the reverse reaction, we say a state of dynamic equilibrium has been reached.

Le Chatelier’s Principle If the conditions of an equilibrium system are changed by changing temperature, pressure or concentration, a process takes place which tends to oppose the effect of the change



An equilibrium may be disturbed by changing any one (or more) of the factors for the equilibrium.    Temperature Concentration (gases and solutions) Pressure (gases only)

Equilibrium Constant If we look at the following GENERAL equation

aA + bB

cC + dD

The expression for the Equilibrium constant – Kc will be as follows:

Kc =

[C]c [ D]d [A]a [ B]b

If A, B, C or D are solids or pure liquids, they must be LEFT OUT of the Kc expression.

  

When Kc has a high value, there will be proportionally more of the substance on the product side - we say the equilibrium lies to the product side (vice versa for a low value). Only temperature alters the Kc value for a specific reaction. If pressure or concentration is changed, the system adjusts the product and reactant concentrations in such a way that Kc stays exactly the same (on condition the temperature does NOT change).

QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question7

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

09-SEP

17:00 -18:00

ELECTROCHEMISTRY & CHEMICAL INDUSTRIES

STUDY NOTES ELECTROCHEMISTRY DIRECT TRANSFER OF ELECTRONS
Example: Zn + CuSO4 Blue → ZnSO4 + Cu clear brown

Observations: a small Zn plate placed in a blue copper sulphate solution gets covered with a brown precipitate of copper and, eventually, the solution turns clear, and the clear solution is zinc sulphate. Reaction in ionic form: Zn + Cu2+ + SO42- → Zn2+ + SO42Oxidation half : Reduction half: Nett equation: Zn + Cu

→ Zn2+ + 2e- (Oxidation is a loss of electrons- OIL) (Reduction is a gain of electron –RIG)
2+

Cu2+ + 2e- → Cu Zn + Cu
2+

→ Zn

+ Cu

THE VOLTAIC OR GALVANIC CELL
Chemical potential energy  Electrical potential energy Example: Zn/Cu Cell: Zinc half cell: Zinc electrode placed in a beaker containing a solution of zinc ions Copper half cell: Copper electrode placed in a beaker containing a solution of copper ions Salt bridge: Tube filled with ions of a very soluble salt (KNO3). Completes the internal circuit and maintains electrical neutrality in the electrolyte solutions. External circuit: Connecting wires that join the Zn electrode to the Cu electrode (can include a voltmeter). Anode – where oxidation occurs Cathode – where reductions occurs

Cell Notation: Zn(s) / Zn2+(1mol∙dm-3) // Cu2+ (1mol∙dm-3) / Cu(s)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

STANDARD ELECTRODE POTENTIALS: THE TABLE o o o o The Table gives standard Emf values and these values were all measured under standard conditions. A reference electrode (standard hydrogen half-cell) was chosen, and all values are measured relative to this. Calculate Emf or E0cell using the equation E0cell = E0cathode - E0anode E0cell for galvanic cells is positive ( spontaneous reactions)

ELECTROLYTIC CELLS
Electrical energy  Chemical Reaction Anode – where oxidation occurs E0cell for Cathode – where reductions occurs

electrolytic cells is negative ( non- spontaneous reactions)

Applications:  Recovering metal from ore (Aluminium from bauxite)  Refining / purifying gold and copper  Electroplating  Production of chlorine in the chlor-alkali industry

EXTRACTION OF ALUMINIUM FROM BAUXITE

Image from: http://lgfl.skoool.co.uk
   Electrolysis of aluminium oxide is hugely environmentally un-friendly. The process uses a very large amount of electricity since the ore needs to be melted. The cryolite is added to lower the melting point of the ore. Carbon dioxide is formed at the anode of the electrolytic cell. Carbon dioxide is a greenhouse gas and as a result contributes to global warming.

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THE PRODUCTION OF CHLORINE


GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

 

Chlorine is manufactured by the electrolysis of brine (NaCl dissolved in water). 2NaCl(aq) + 2H2O(l) --> Cl2(g) + H2(g) + 2NaOH(aq) Sodium hydroxide is produced at the same time as chlorine. We call this a byproduct). Sodium hydroxide is then used in making soap

There are 3 different types of cells: o Mercury cell o Diaphragm cell o Membrane cell

BATTERIES
Batteries are GALVANIC (VOLTAIC) cells. They convert chemical energy into electrical energy through a spontaneous Redox reaction. Cell Capacity - the ability of a fully charged battery to deliver a specific quantity of current over a specific period of time (minutes or hours). Q = I∆t where Q is measured in Amp. hours (A·h) Cell emf gives the voltage that the battery can provide. the voltage and charge together gives the amount of energy (work done) the battery can provide. W = VQ or W = VI∆t

Where W is the work done (energy transferred) and measured in Joules (J)

Primary and Secondary cells Primary Cells - these are cells that can be discarded after use. - they become “flat” and therefore, can no longer produce electrical energy required to make an appliance work.
The Leclanche Cell The very familiar “torch battery” is an example of the Leclanche cell and is a primary cell. Cathode - is a carbon rod running through the centre of the cell surrounded by a paste of manganese dioxide (MnO2) Anode - the zinc metal casing of the cell acts as the anode. Electrolyte - a paste of ammonium chloride (NH4Cl ) and zinc chloride (ZnCl2)

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At the anode : Zn Zn2+ +

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES
2e Mn2O3 + H2O + 2NH3

At the cathode : 2NH4+ + 2MnO2 + 2e Secondary cells

 

these are cells that can be recharged by driving a current through them this converts electrical energy into chemical energy by reversing the chemical reaction, i.e. the products of the reaction during discharge are reconverted into the starting materials

The Lead Acid cell (the car battery) Anode - lead alloy grids (Pb) Cathode - grids packed with lead dioxide (PbO2) Electrolyte - dilute sulphuric acid (H2SO4)

At the anode :

Pb

+

SO42-

PbSO4 PbSO4

+ +

2e 2H2O

At the cathode : PbO2 + SO42- + 4H+ + 2e Overall : Pb + PbO2 + 2H2SO4

2PbSO4

+

2H2O

FERTILISERS In order to make fertiliser, we need to manufacture nitric acid, ammonia and sulphuric acid. All of these industrial processes make use of our understanding of equilibrium and rates. Let us investigate these industrial processes further.

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SULPHURIC ACID
Uses of sulphuric acid     

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Acts as a drying agent – used by chemical engineers to mop up water. Used as an electrolyte in car batteries (lead accumulator batteries). Used in the recovery of metals such as uranium and copper. Used to clean metal surfaces. Used to produce fertilisers. THE CONTACT PROCESS S (s) + O2 (g)  SO2 (g) SO2 (g) + O2 (g)  2 SO3 (g) (V2O5 catalyst) SO3 (g) + H2SO4  H2S2O7 H2S2O7 + H2O  2 H2SO4

   

Sulphur is burnt in oxygen. Sulphur dioxide is further reacted with oxygen in contact with a vanadium pentoxide catalyst to form sulphur trioxide. This is a reaction that is governed by equilibrium principles. Sulphur trioxide is then added to sulphuric acid (note only 1 molecule) to form pyrosulphuric acid/fuming sulphuric acid/oleum. Pyrosulphuric acid is mixed with water and sulphuric acid is formed (note 2 molecules). One molecule of sulphuric acid is ‘invested’ to make two molecules.

AMMONIA Ammonia is produced by means of the Haber process. This process is also governed by equilibrium principles. HABER PROCESS N2 (g) + 3 H2 (g)  2 NH3 (g) (iron oxide catalyst) ΔH = -46 kJ.mol-1 Temperature: Exothermic reaction. Lowering the temperature shifts the equilibrium to the right. However, lower temperature also slows the reaction down so an optimum temperature must be found (600 K - 800 K) Pressure: 4 molecules on the left and 2 molecules on the right; therefore, high pressure favours the forward reaction. (350 atm) Concentration: Ammonia is continuously removed, to reduce ammonia concentration and shift the equilibrium to the right. Uses of ammonia      As a cleaning agent when dissolved in water. In the manufacture of fertilisers. Ammonium salts are highly soluble in water so they Can be dissolved and absorbed by plants, thus making nitrogen available to the plant. In the manufacture of ammonium carbonate used in the textile industry. In the manufacture of nitric acid.

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NITRIC ACID

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

Nitric acid is produced by the Ostwald process. THE OSTWALD PROCESS 4 NH3 (g) + 5 O2 (g)  4 NO (g) + 6 H2O 2 NO (g)+ O2 (g)  2 NO2 (g) 4 NO2 + 2 H2O + O2  4 HNO3

   

Ammonia is oxidised to nitrogen monoxide and water. Nitrogen monoxide is further oxidised to nitrogen dioxide. Nitrogen dioxide is then added to water from the first step and oxygen to make nitric acid. Nitrate salts are highly soluble in water and, therefore, assist in allowing nitrogen to be absorbed by plants.

CHALLENGES FOR THE CHEMICAL INDUSTRY
     Safety issues regarding the transport of chemicals Pollution control Waste disposal Energy consumption Commercial fertilisers are described in terms of their relative proportions of nitrogen (N), phosphorus (P) and potassium (K). NPK numbers are printed on fertiliser bags. E.g. 5:13:5 means the content of the bag is 5% nitrogen 13% phosphorus 5% potassium Sources of potassium:  Salts containing potassium are referred to as POTASH when used as fertilisers. Mined potassium salts, such as KNO3 and K2SO4 are used. Sources of phosphorus  bone meal that was acidified to yield phosphoric acid H3PO4  mined calcium phosphate Ca3(PO4)2  Calcium phosphate is insoluble in water and cannot be absorbed by plants. Calcium phosphate is treated with sulphuric acid to yield water soluble superphosphate that can be absorbed.

THE FERTILISER INDUSTRY


 



Ca3(PO4)2 + H2SO4 → 2CaSO4 + Ca(H2PO4)2

EUTROPHICATION
    Extensive utilisation of fertilisers leads to pollution of surface and ground water and eutrophication of lakes, dams and rivers. This is mainly due to fertiliser wash off Eutrophication is caused by excess phosphates and nitrates in rivers, lakes and dams. Phosphates promote the growth of algae which cover the surface of the water and kill aquatic plants below. Bacteria decompose the dead aquatic life causing oxygen levels in the water drop to such a low level that aquatic animals suffocate and die.

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QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 8, 9, 10, 11 Diagrams for Question 8 (Nov 2011 P2)

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Diagrams for Question 9 (Nov 2011 P2)

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Diagrams for Question 10 (Nov 2011 P2)

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Diagrams for Question 11 (Nov 2011 P2)

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RADIO BROADCAST
SPRING SCHOOL
GRADE 12 PHYSICAL SCIENCES

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SPRING SCHOOL 01-OCT 10:00 -11:00
STUDY TIPS:  

MECHANICS

      

Print out a copy of the information sheet and make sure you know where to find the equations and constants. This will save you time in the exam. Make a list of laws and principles using the memos from previous exam papers or a textbook. You must learn these and be able to recall them word for word. There are no part marks allocated in questions that ask you to state a law or principle. Draw a sketch diagram for each question. Fill in all the known information. Use mechanics equations to find the unknown. Always work with SI units. Every answer must have the correct unit. Remember the term “from rest” means the initial velocity is 0 m.s-1 The acceleration due to gravity, g = 9,8m.s-2, always acts down. It cannot change direction or size. Any object falling down or thrown up experiences acceleration downwards. At the maximum height above the ground, the velocity of a projectile is 0 m.s -1 but its acceleration is still 9,8m.s-2 downwards. When you sketch graphs make sure you label the axes and give the SI unit. Make sure you that when answering questions about vector quantities, you have a positive answer, the correct SI unit and the direction in your answer.

QUESTIONS FOR DISCUSSION
Feb / Mar 2011 P1 Question 3 & 5

ON AIR COMPETITION QUESTION What impulse is equal to? A B C D change in velocity of a body. rate of change of net force product of net force and time the force is applied product of mass and velocity of the body

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Diagram for Question 3 (Feb/ Mar 2011)

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Diagram for Question 5 (Feb/ Mar 2011)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

02-OCT

10:00 -11:00

ORGANIC CHEMISTRY

STUDY TIPS:     
You must learn the IUPAC rules for naming organic molecules. You must learn the prefixes for 1-8 carbons in a chain and the suffixes for the different homologous series. Make sure you can identify the functional group for each homologous series. When you are asked to draw a structural formula of a molecule, make sure you show all the bonds. Each carbon must have 4 bonds. A good way to practise naming and drawing is to find all the isomers of a molecular formula. Start with C5H12 and then increase the number of carbons and include different functional groups. Remember the steps of the scientific method and how to do a proper scientific investigation. You need to be able to formulate an investigative question, state an hypothesis, identify variables, control variable, interpret results and draw a conclusion from the results. Draw up a table of the physical properties of organic molecules, the intermolecular forces present and describe the trend for increasing chain length, increasing branches using different functional groups. Use flow diagrams to learn the different types of organic reactions.

 

QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 1.1, 1.2 Nov 2011 P2 Question 2.1, 2.2 and 2.3 Feb 2011 P2 Question 4

COMPETITION QUESTION
Which ONE of the following pairs of reactants can be used to prepare the ester propyl ethanoate in the laboratory?
A B C D propanol and ethanoic acid propane and ethanoic acid ethanol and propanoic acid propane and ethanol

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Diagram for Question 2.3 (Nov 2011 P2)

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Diagram for Question 4 (Feb 2011 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

03-OCT

10:00 -11:00

ELECTRICITY

Study Tips:
      Make sure you revise all your Grade 11 work on electrostatics, capacitors, electromagnetic induction and electric circuits. Pay special attention to learning Coulomb’s Law, Faraday’s Law and Ohm’s Law. Recognise that the equations given on your information sheet describe the laws and the relationship between the variables. When two variables are directly proportional, if one doubles the other doubles too. When two variables are inversely proportional, if one doubles the other halves. For Coulomb’s Law, force is inversely proportional to distance between the charges ). This means that if we double the distance, the force will decrease by 4 squared, ( times. If you want to double the force, you need to reduce the distance by √2 times Practise drawing circuit diagrams. Make sure you can identify parts of the circuit where the current is the same (ammeter readings) and where potential difference is the same (voltmeter readings). For electric circuit questions, there is usually more than one way to find the correct answer. When doing previous exam paper questions, always check your answer using an alternative method. For electric motors and generators, make sure you can determine the direction of motion, magnetic field or current. The right hand rule is preferred for both. However some people still use the left hand rule for motors and the right hand rule for generators. Select one method and stick to it. Remember the electric motor has a split ring commutator and the AC generator has slip rings.

  



QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 2.6 and 2.8 Nov 2010 P1 Question 9 Feb 2011 P1 Question 9

COMPETITION QUESTION
What is the SI unit of measurement of the rate of flow of charge in a conductor? A B C D watt volt ampere coulomb

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Diagram for Question 2.6 (Nov 2011 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagram for Question 2.8 (Nov 2011 P1)

Diagram for Question 9 (Nov 2010 P1)

Diagram for Question 9 (Feb 2011 P1)

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Diagram for Question 9 (Feb 2011 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

04-OCT


10:00 -11:00

RATES & CHEMICAL EQUILIBRIUM

STUDY TIPS:
Remember the steps of the scientific method and how to do a proper scientific investigation. You need to be able to formulate an investigative question, state an hypothesis, identify variables, control variable, interpret results and draw a conclusion from the results. For rates of reaction you must be able to explain the how changing temperature, concentration, particle size (surface area) and a catalyst affects the rate using collision theory Revise the following graphs: potential energy vs. reaction co-ordinate for exothermic and endothermic reactions, the Maxwell-Boltzmann energy distribution curve, mass of reactants vs. time during a reaction, volume of gas collected during a reaction vs. time and reaction rate vs. time for reversible reactions in chemical equilibrium. For chemical equilibrium calculations, make sure you write down the Kc expression for the given balanced chemical equation. Do not write down the general formula. Remember to include only the concentration of gases and aqueous solutions. Do not include solids or pure liquids. For Kc calculations, make sure that all the information given is in the same units. It is best to have all quantities in moles. Use the RICE table to set out your work neatly. Don’t forget to convert all moles into concentration by dividing by volume in the final step of the table. Remember only TEMPERATURE will change the value of Kc Revise interpreting and sketching graphs of concentration vs. time for systems in chemical equilibrium. Recognise what has caused a change in the position of equilibrium using a graph. State and explain Le Chatelier’s principle.

 





  



QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 2.4, 2.5 and 2.6 Feb 2011 P2 Question 7.4 - 7.6

COMPETITION QUESTION
A chemical reaction reaches equilibrium. Which ONE of the following statements regarding this equilibrium is TRUE?
A B C D The concentrations of the individual reactants and products are constant. The concentrations of the individual reactants and products are equal. The concentrations of the individual reactants are changing continually. The concentrations of the individual products increase until the reaction stops.

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Diagram for Question 2.5 (Nov 2011 P2)

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Diagram for Question 2.6 (Nov 2011 P2)

Diagram for Question 7.4 (Feb 2011 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

05-OCT


10:00 -11:00

WAVES, LIGHT & SOUND

STUDY TIPS:

      

Remember that frequency and wavelength are inversely proportional to each other. A wave with a big wavelength will have a low frequency, and a wave with a small wavelength will have a high frequency. For sound, frequency is directly proportional to pitch and amplitude is directly proportional to loudness. When a source of sound moves towards a stationary observer, the frequency the observer hears is greater than the frequency of the source (higher pitch). When a source of sound moves away from a stationary observer, the frequency the observer hears is less than the frequency of the source (lower pitch). Red shift is an example of the Doppler Effect. Light from stars moving away from Earth has a smaller frequency than expected. The line emission spectra are all shift towards the red end of the spectrum. Huygens’ Principle is used to explain diffraction. Every set of points on a wavefront acts as a source of wavelets. The wavelets interfere with each other to produce the next wavefront. Interference is evidence that light has a wave nature. The photoelectric effect is evidence that light has a particle nature.

QUESTIONS FOR DISCUSSION
Nov 2011 P1 Question 2.4, 2.5, 2.9 and 2.10 Feb 2011 P1 Question 6

COMPETITION QUESTION
Which ONE of the following is the main principle applied when measuring the rate of blood flow or the heartbeat of a foetus in the womb?
A B C D Photoelectric effect Doppler Effect Huygens' Principle Diffraction

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Diagram for Question 2.4 (Nov 2011 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagram for Question 2.5 (Nov 2011 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

07-OCT


17:00 -18:00

ELECTROCHEMISTRY

STUDY TIPS:
There are two Standard Reduction Potential tables given in the information sheets. You must make sure that you work with the one that you have used at school, otherwise you will mix the oxidation and reduction around. Look for the position of fluorine (F2) - it is the strongest oxidising agent. Reducing Agents donate electrons and have a negative E0cell Oxidising Agents take electrons and have a positive E0cell In electrochemical / voltaic / galvanic cells and electrolytic cells, the anode is the electrode where oxidation takes place and the cathode is the electrode where reduction takes place. (Anode – Oxidation: vowels go together). The standard conditions for a galvanic cell are: a temperature of 250C, a concentration of 1 mol.dm-3 and a pressure of 1 atmosphere for gases. In a galvanic cell, the voltmeter reading will decrease as the concentrations of the electrolyte in the half cells change. When the concentrations are constant chemical equilibrium has been reached and the voltmeter reading is 0V. When learning electrochemistry include the chlor-alkali industry and batteries in this section.

     

QUESTIONS FOR DISCUSSION
Nov 2011 P2 Question 2.7, 2.9 and 2.10 Feb 2011 P2 Question 8, 9, 10

COMPETITION QUESTION
Consider the electrolysis of copper (II) chlorine. Which statement about the positive electrode is NOT true? A B C D The electrode is the cathode of the cell. Chlorine gas is produced. Oxidation takes place at this electrode. The electrode is the anode of the cell.

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Diagram for Question 8 (Feb 2011 P2)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Diagram for Question 9 (Feb 2011 P2)

PRELIM REVIEW

During this week we will be answering questions from various provincial preliminary examination papers. Please email questions that you need help with to [e-mail] before the radio broadcast. You can also phone in on the helpdesk number, 086 1058 262, to speak to a teacher and to answer the daily on air competition question. We will post questions we receive from learners on the Facebook events page so that you can follow.

08-Oct 09-Oct 10-Oct 11-Oct 14-Oct

18:00 -19:00 Mechanics 18:00 -19:00 Organic Chemistry 18:00 -19:00 Electricity 18:00 -19:00 Rates & Chemical Equilibrium 17:00 -18:00 Chemical Industries

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RADIO BROADCAST pRELIM REVIEW
GRADE 12 PHYSICAL SCIENCES

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

During this week we will be answering questions from various provincial preliminary examination papers. Please email questions that you need help with to [e-mail] before the radio broadcast. You can also phone in on the helpdesk number, 086 1058 262, to speak to a teacher and to answer the daily on air competition question. We will post questions we receive from learners on the Facebook events page so that you can follow.

PRELIM REVIEW

08-Oct 09-Oct 10-Oct 11-Oct 14-Oct

18:00 -19:00 Mechanics 18:00 -19:00 Organic Chemistry 18:00 -19:00 Electricity 18:00 -19:00 Rates & Chemical Equilibrium 17:00 -18:00 Chemical Industries

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RADIO BROADCAST exam revision
PAPER 1 pHYSICS GRADE 12 PHYSICAL SCIENCES

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

EXAM REVISION: PAPER 1 (PHYSICS)
For the two days before you write the final exam, we will work through the solutions to questions taken from the Feb / Mar 2012 exam paper. Please call in or send an email to let us know with which questions you are struggling. 23-Oct 17:00 -18:00 Motion and Doppler Effect Questions for discussion Feb/Mar 2012 P1 Question 2.3, 3 and 6 Diagram for Question 2.3 (Feb 2012 P1)

Diagram for Question 3 (Feb 2012 P1)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

23-Oct 18:00 -19:00 Momentum and Work Energy & Power Questions for discussion Feb/Mar 2012 P1 Question 2.1, 2.2, 4 and 5 Diagram for Question 4 (Feb 2012 P1)

Diagram for Question 5 (Feb 2012 P1)

24-Oct 17:00 -18:00 Electricity Questions for discussion Feb/Mar 2012 P1 Question 2.6 – 2.8, 8 and 9 Diagram for Question 2.6 (Feb 2012 P1)

Diagram for Question 2.8 (Feb 2012 P1)

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Diagram for Question 2.8 (Feb 2012 P1)

Diagram for Question 8 (Feb 2012 P1)

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Diagram for Question 9 (Feb 2012 P1)

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

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24-Oct 18:00 -19:00 Electromagnetism Questions for discussion:

GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Feb/Mar 2012 P1 Question 2.9 – 2.10, 7, 10 and 11

Diagram for Question 2.9 (Feb 2012 P1)

Diagram for Question 10 (Feb 2012 P1)

Diagram for Question 11 (Feb 2012 P1)

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RADIO BROADCAST exam revision
PAPER 2 cHEMISTRY GRADE 12 PHYSICAL SCIENCES

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

EXAM REVISION: PAPER 2 (CHEMISTRY)
For the two days before you write the final exam, we will work through the solutions to questions taken from the Feb / Mar 2012 exam paper. Please call in or send an email to let us know the questions with which you are stuggling.

26-Oct

17:00 -18:00

Organic molecules & properties

Questions for discussion:
Feb/Mar 2012 P2 Question 2.1 -2.3, 3 and 4 Diagram for Question 2.2 (Feb 2012 P2)

Diagram for Question 2.3 (Feb 2012 P2)

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Diagram for Question 3 (Feb 2012 P2)

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Diagram for Question 4.2 (Feb 2012 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

26-Oct

18:00 -19:00

Organic Reactions

Questions for discussion:
Feb/Mar 2012 P2 Question 5 Diagram for Question 5 (Feb 2012 P2)

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

28-Oct

17:00 -18:00

Rates & Chemical Equilibrium

Questions for discussion:
Feb/Mar 2012 P2 Question 6 & 7 Diagram for Question 6 (Feb 2012 P2)

28-Oct

18:00 -19:00

Electrochemistry & Chemical Industries

Questions for discussion:
Feb/Mar 2012 P2 Question 8 - 11
Diagram for Question 8 (Feb 2012 P2)

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Diagram for Question 9 (Feb 2012 P2)

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Diagram for Question 10 (Feb 2012 P2)

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RADIO BROADCAST lISTENER fEEDBACK cOMPETITION 83

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GRADE 12 PHYSICAL SCIENCES RADIO BROADCAST NOTES

Listener’s Feedback Competition
Complete and return this form and stand a chance to win an Apple iPad 3. 1. What grade are you in? Grade 10 Grade 12

2. How did you hear about Mindset Learn Xtra Radio Revision (tick all that apply)? A friend My school/teacher The radio A newspaper The Mindset website The Mindset Facebook page 3. Which Mindset Learn Xtra Radio Revision programmes did you listen to? Please tick all boxes that apply. Grade 12 Mathematics Physical Sciences English First Additional Language Mathematics Physical Sciences English First Additional Language Grade 10

4. Please rate how much you agree with each of the following statements by placing a tick in the relevant box where 1 is strongly disagree and 5 is strongly agree. 1 The radio broadcasts were generally clear and free from interference The Learner Guide book was helpful. The pace of the radio shows was just right – not too fast and not too slow. The presenters spoke clearly and were easy to understand. The content presented on TV and in the Learner Guide was at the right level – not too easy and not too difficult. Topics were covered fully and all important areas were dealt with. Working through exam questions helped me understand the content better. The radio shows were enjoyable and informative. I would recommend this revision programme to other learners. The revision was very helpful in preparing me for the exams. I feel more confident about writing exams now than I did. 5. Had you ever heard of Mindset, Mindset Learn or Mindset Learn Xtra before this broadcast? Yes No 84 MTN Learn powered by 2 3 4 5

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5. Had you ever heard of Mindset, Mindset Learn or Mindset Learn Xtra before this broadcast? Yes No 6. Had you ever used any Mindset content before broadcast? Yes No 7. Have you ever visited the Mindset Learn website (www.mindset.co.za/learn)? Yes No 8. Have you ever visited the Mindset Learn Facebook page www.facebook.com/learnxtra)? Yes No 9. Are there any other general comments you would like to make?

_______________________________________________________________________ Your name: _________________________________________________________________________ Your contact number: __________________________________________________________________ Your address: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Competition closes: 9 November 2012 at 12 noon. Entries to be sent to [e-mail], 086 101 6463 or Mindset Network – PO Box 4635, Randburg. 2125. You can also provide your feedback and enter the competition at www.mindset.co.za/learn/win. Terms and conditions: Full competition terms and conditions available at www.mindset.co.za/learn/win.

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