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Please read before you come for the next lesson

Additional Notes on significant figures

When we use an equipment to take measurement, it is important to be honest when reporting a measurement, so that it does not appear to be more accurate than the equipment used to make the measurement allows. To achieve this, we can control the number of significant figures used to report the measurement.

When we look at a number, its first significant figure is the first digit from the left, other than 0. E.g. -in the number 539 the first significant figure is 5
-in the number 0.06189 the first significant figure is 6

The number of significant figures is the number of digits counting from the left from the first significant figures.

By looking at the examples below, generate some rules in determining the number of significant figure of a number. * in the number 0.06189 there are four significant figures * in the number 2390001 there are seven significant figures * in the number 2390000 there are three (or seven) significant figures** * in the number 2390000.00 there are nine significant figures

The rules that I can generate are:

When using calculator to solve a problem, the answer shown on the calculator may consist of many digits. But not all the numbers that appear on the calculator are ‘significant’. You may just want to express your answers in, for example, three significant figures.

The examples below show how you should express your answer in 3 significant figures. Fill in the blanks. * 981.2645 should be written as 981
* 2.365789 should be written as 2.37
* 4321789.1 should be written as 4320000
* 7.1000000 should be written as __________
* 3629.3309 should be written as __________
* 0.0056793 should be written as __________

Self directed learning:
Take the quiz to test your understanding on significant figure:...

...SignificantFigures in Measurement and Calculations
A successful chemistry student habitually labels all numbers, because the unit is important. Also of great
importance is the number itself. Any number used in a calculation should contain only figures that are
considered reliable; otherwise, time and effort are wasted. Figures that are considered reliable are called
significantfigures . Chemical calculations involve numbers representing actual measurements. In a
measurement, significantfigures in a number consist of:
Figures (digits) definitely known + One estimated figure (digit)
In class you will hear this expressed as "all of the digits known for certain plus one that is a guess."
Recording Measurements
When one reads an instrument (ruler, thermometer, graduate, buret, barometer, balance), he expresses
the reading as one which is reasonably reliable. For example, in the accompanying illustration, note the
reading marked A. This reading is definitely beyond
the 7 cm mark and also beyond the 0.8 cm mark. We
read the 7.8 with certainty. We further estimate that
the reading is five-tenths the distance from the 7.8
mark to the 7.9 mark. So, we estimate the length as
0.05 cm more than 7.8 cm. All of these have meaning
and are therefore significant. We express the reading as 7.85 cm, accurate to three...

...SignificantFigure Rules
Significantfigure rules are really "rules of thumb" for how to handle the results of calculations so as
not to introduce or lose precision in performing a mathematical operation. These rules are not always
correct for all situations. However, in most cases, following the significantfigure rules will yield a
good result.
Rules concerning zero
A zero between twosignificantfigures is significant. The number 203.2 consists of four significantfigures.
A Zero to the right of a digit beyond the decimal point is a significantfigure. The number 14.720 consists of five significantfigures. (Note the zero would not be necessary to set the decimal point, thus it is significant).
A zero is not significant if it merely fixes the decimal point. The number 0.031 contains two significantfigures, the zero sets the decimal point and is not significant. In the number 1200 the zeros may or may not be significant.
The digits and zeros shown in the decimal part of standard exponential numbers are significant.
3.2 x 10-2 indicates two significantfigures.
1.2 x 103 indicates two significant...

...Introduction to Chemistry Laboratory:
A Lesson on Tools, Techniques and Measurements
PURPOSE: The purpose of this set of experiments (3 total) is to become familiar with the common types of laboratory
glassware and equipment, and how to obtain and analyze data from these items.
LEARNING OBJECTIVES: By the end of this experiment, the student should be able to demonstrate the following
proficiencies:
1. Know which glassware (beakers, burettes, pipettes, graduated cylinders, flasks, etc) should be used in various
circumstances.
2. Know how to “correctly” measure volume and mass (weight).
3. Become familiar with significantfigures and its relationship to measurements and data recording (significantfigures).
4. Become familiar with the errors, precision and accuracy associated the various measurement tools and techniques.
5. Determine the density of liquids and solids.
6. Determine the best-fit straight line as a method to examine linear relationships and to use this relationship as a
predicative model such as in the determination of the percent copper and zinc in pennies based on density
measurements.
7. Record laboratory data and observations.
MATERIALS:
Erlenmeyer Flasks
o 125 mL
o 250 mL
beakers
o 100 mL
graduated cylinders
o 10 mL
o 25mL
Burette
o 50 mL
Volumetric pipettes
o 10 mL
Measuring pipet
o 10 mL
Burette clamp and stand
Various liquids and solids for density determination...

...will be caught.
A. SIGNIFICANTFIGURES (10 pts.)
(Show the actual results first before rounding off the digits into their proper significantfigures.)
A.1. Determine the number of significantfigures in each numerical value below. (Assume all values are measurements.)
1. 357 ml
2. 1.0600 L
3. 0.000 501 g
4. 23, 000 tons
5. 1.8000 X 105 mi
A.2. Perform the following arithmetic operations and express the answer to the correct number of significantfigures
1. 0.392 + 51.4
2. (5260 x 12.0) / 2.1
3. 273.15 – 28.3
4. 8.63 x 0.58
5. 6.02 / 3.0
B. SCIENTIFIC NOTATION (10 pts.)
B.1. Convert the following numbers from scientific notation to normal notation
1. 8.59 x 10 -3
2. 2.76 x 10 2
3. 2.76 x 10 -2
4. 7.2 x 109
5. 7.2 x 10-9
B.2. Convert the following numbers from normal notation to scientific notation
1. 0.000 000 000 8304
2. 9,500,000
3. 0.013
4. 58.3
5. 0.583
C. DENSITY and SPECIFIC GRAVITY (20 pts.)
(Observe proper SignificantFigures in the answer)
1. Calculate the mass in grams of 15.0ml of a saline solution that has a density 1.05 g/ml
2. Copper has a density of 8.96 g/ml. Calculate the volume occupied by 125.0 g of copper.
3. A. If the density of a liquid is 0.80 g/ml, what is its specific gravity?
B. If the...

...p)
5. An athlete’s time for a race was 43.78secods.
(a) Write this time correct to
(i) One decimal place
(ii) Correct to tens
(b) Write 43.78 and answers to (a) part (i) and (ii) in the ascending order.
6. Change to decimal. Write down calculator display correct to 4dp.
7. A car costs £7552. Write the cost of the car nearest 100pounds.
8. The mass of a bottle is 483gms. Write the mass correct to hundred grams.
9. Round off the following numbers correct to the number of significantfigures indicated within brackets.
(a) 8.043 (2s.f.)
(b) 4.13865 (2s.f.)
(c) 0.04036 (1s.f)
(d) 0.03064 (3s.f)
(e) 64.074 (1s.f)
(f) 71.97 (3s.f)
(g) 2467 (2s.f)
10. Calculate the following and write correct to 1s.f
(a)
(b)
(c)(4.742+6.292)3
(d)
11. The diameter of the sun is 1 392 530
kilometres. Write this value correct to
4 significantfigures.
12. Write the number 2381.597 correct to
(a) 3 significantfigures,
(b) 2 decimal places,
(c) the nearest hundred.
...

...has the fewest number of significantfigures?
A. 12.80 m
B. 0.1280 m
C. 0.001280 m
D. 1280 m
4. Which quantity is an exact number?
A. 3 cars
B. 1,000 m
C. 2 L
D. 453.6 g
5. The number 0.0035880 expressed correctly using scientific notation is
A. 0.0035889.
B. 3.5880 × 103.
C. 3.5880 × 10–3.
D. 3.5880 × 10–4.
6. The measurement 78,005,760 expressed correctly using scientific notation is
A. 7.8005760 × 107.
C. 7.8 × 107.
D. 7.800576 × 10–7.
E. 7.800576 × 107.
7. When 4.870 × 10–3 is correctly converted to its standard form the number becomes _____.
A. 4870
C. 0.00487
D. 0.004870
E. 0.0004870
8. Which number is the largest?
A. 4.38 × 103
B. 4.38 × 102
C. 4.38 × 10–3
D. 4.38 × 10–2
E. 438
9. Which number is the smallest?
A. 4.38 × 103
B. 4.38 × 102
C. 4.38 × 10–3
D. 4.38 × 10–2
E. 438
10. When 0.022189 is correctly rounded to two significantfigures the number becomes _____.
A. 0.02
B. 0.022
D. 0.023
11. When 5.5490× 108 is correctly rounded to three significantfigures the number becomes _____.
A. 5.55
B. 5.55 × 108
D. 554
E. 5.54 × 108
12. Which number has four significantfigures?
A. 3.978
B. 0.780
C. 0.0085
13. What is the correct answer to this calculation, reported using the proper number of significantfigures: 38.251 + 73.1?
A. 111
B. 111.3
C....

...To what extent should the private lives of public figures be the subject of media coverage?
Public figures are those who have got their positions through the choice of their people, people who have been elected to lead the country or who hold responsible positions in their societies. They are people like royalty, presidents, prime ministers, ministers and members of parliament. To this we could add judges, public prosecutors and other important civil servants. It is true that they are often the subject of news hounds. Public figures are often reported at length on all their activities and quite a lot of it concerns their private lives. The question is should their public lives be an open book and should we all be concerned about what they do in their own time? Can we draw a line and say that they should be just like other top management people of large corporations. These people seem to be at liberty to do what they like in their own time. Few people, even the media, care if they cheat on their wives as long as they are honest in their jobs and do not break the law. However there seems to be lot of concern about what a minister does - at all times.
First of all it seems logical that powerful people need to be watched more closely than ordinary people. The reasons are simple. They could abuse their powers. This has happened quite often all over the world. Also, if they fall, they will take many down with them. If a minister...

...
Sports Figures and Celebrities: Who Is The Right Role Model?
Krista Nicole Valley
ENG 122: English Composition II
Prof: Heather Nielson
February 22, 2015
I. Introduction
A: Thesis Statement
While celebrities and sports figures are more likely to be role models to children, it is up to the child to decide whether to base their decision on likes and beliefs, or looks.
II. Body paragraph #1- Topic Sentence #1
When it comes to choosing a sports role model, a lot of children are going to choose someone who they can relate to based on the sports they are currently in, or sports they admire.
A: Supporting Evidence
According to a recent study done by the European Physical Education Review (2005), only a small percentage of those high school students chose a sports figure as their role model. But, if a sports figure is chosen as a role model it is because that child is into the same sports that the sports figure is in.
B: Explanation
Kids are going to choose a sports role model based on the sports that they like. As an example, my favorite sport is colorguard, and my role model is my mentor Harley bland. He has been a director for over 10 years, and taught me everything that I know.
C: So What
It can sometimes be difficult to be aware of who a child chooses as their role model, but a parent can keep up to date by talking to their child, and seeing what sports they...