Discuss why hydrogen bonding is essential for life Throughout biochemistry there are many bonds without which life as it is on earth today would not be possible. One of the most important bonds of these is the hydrogen bond‚ a weak chemical bond that is present in essential biological molecules such as water and polypeptides. A hydrogen bond is defined by Campbell and Reece as occurring when a hydrogen atom is covalently bonded to an electronegative atom but attracted to another electronegative
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1. | | | What is the pressure‚ in atm‚ of a tank of gas with a regulator that reads 1250mmHg? | | | Student Response | Correct Answer | A. | 1.64 | | B. | 490 | | C. | 1.79 | | D. | 0.608 | | E. | 1.25 | | | Score: | 0/1 | | | 2. | | | A 147.9-L sample of dry air is cooled from 88.0°C to 22.1°C while the pressure is maintained at 2.85 atm. What is the final volume in L? (Do not type the units.) | | | Student Response | Correct
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M10/4/PHYSI/SP2/ENG/TZ1/XX+ 22106511 Physics standard level PaPer 2 Candidate session number Monday 10 May 2010 (afternoon) 0 1 hour 15 minutes 0 INSTRUCTIONS TO CANDIDATES • • • • • Write your session number in the boxes above. Do not open this examination paper until instructed to do so. Section A: answer all of Section A in the spaces provided. Section B: answer one question from Section B in the spaces provided. At the end of the examination‚ indicate the
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Tminimum = 45 – 20 = 25 0C * Calculate the number moles of copper sulphate reacted: number of moles = concentration x volume = 0.5 x 0.025 = 0.0125 mol * Calculate energy released during the reaction (Q): Q = mass of CuSO4 x specific heat capacity x ΔT = 25 x 4.2 x 25 = 2625 J * Calculate ΔH for the reaction (energy change is negative because the reaction was exothermic): ΔH = -Q / number of moles = 2625 / 0.0125 = 210 kJmol-1 ‘Absolute Uncertainty’ = abs/unc ‘Percentage Uncertainty’
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how to determine the caloric content of food by creating our own calorimeter. Measuring the energy content of three different food samples by using the change in water temperatures from the heat given off while burning the sample. To verify our results much further — equations‚ such as energy and heat capacity calculations‚ helped us establish on such results. As a result of the experiment‚ I learned and understand better the importance of choosing food with the right caloric content to get us through
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dollars? A) $63.54 B) $16.79 C) $4.44 Your car needs 12.00 gallons. How much will your D) $67.15 5) Determine the final temperature of a gold nugget (mass = 376 g) that starts at 398 K and loses 4.85 kJ of heat to a snowbank when it is lost. The specific heat capacity of gold is 0.128 J/g°C. A) 398 K B) 133 K C) 377 K D) 187 K E) 297 K 6) Calculate the atomic mass of gallium if gallium has 2 naturally occurring isotopes with the following masses and natural abundances:
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Cambridge International Examinations Cambridge Ordinary Level * 8 7 0 6 7 3 2 3 4 6 * 5054/32 PHYSICS Paper 3 Practical Test May/June 2014 2 hours Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your Centre number‚ candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples‚ paper
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An intensive property is a physical quantity whose value does not depend on the amount of the substance for which it is measured. For example‚ the temperature of a system in thermal equilibrium is the same as the temperature of any part of it. If the system is divided the temperature of each subsystem is identical. The same applies to the density of a homogeneous system: if the system is divided in half‚ the mass and the volume change in the identical ratio and the density remains unchanged. According
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able to store and absorb heat. With this property‚ heat lost is able to be prevented during night time and maintaining thermal comfort of interior during day time. In addition‚ bricks also consist of the characteristics of acoustic isolation. As bricks has greater density‚ thus it is able to provide higher acoustic insulation. Moreover‚ brick has high efficiency in revisiting and preventing the spread of fire due to its low thermal conductivity and high heat capacity. Low thermal conductivity
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more energy in combustion reaction than the less alcoholic hydrocarbons compounds. Equipment: Different types of alcohols in spirit burner (CH4‚ C2H6‚ C3H8‚ C4H10‚ C5H12)‚ Thermometer‚ water‚ beaker‚ scale‚ measuring cylinder‚ tripods‚ clamp‚ gauze‚ heat mat‚ lighter or matches. Hazard: Most of alcohol we using are flammable‚ irritant‚ toxic and harmful. 1 provide spirit burners which have removable glass caps‚ this makes it easier and safer to extinguish the flames. 2 Make sure the wick fits tightly
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