NAME Student No. Section (circle one): A01 (Lipson) A02 (Briggs) A03 (Cartwright) UNIVERSITY OF VICTORIA Version A CHEMISTRY 102 Mid-Term Test I February 3, 2012 Version A This test has two parts: (A Data Sheet is provided with the exam.) PART I is a multiple choice examination and is worth 26 marks. The answers for the 14 questions in this part must be coded on the optical sense form using a soft leaded pencil. PART II has written answer questions and is on the last 3 pages and is worth 24 marks. Answer these questions on this examination paper. Part II Score Exam results Score 1 [8 marks] Part I [26 marks] 2 [5 marks] Part II [24 marks] 3 [4 marks] Total score [50 marks] 4 [4 marks] Percent score 5. [3 marks] Hand in this entire test paper as well as your optical sense form at the end of the examination period (60 minutes) PART I Multiple Choice. Select the best response from the choice provided. Mark only one response for each question. 1. This is exam version A. Mark "A" as the answer to question 1 on your bubble sheet. 2. To increase the volume of a fixed amount of gas from 200 ml to 400 ml A. increase the temperature from 20.0 to 40.0 C at constant pressure B. increase the pressure from 2.00 to 4.00 atm at constant temperature C. reduce the temperature from 527 C to 127 C at constant pressure D. reduce the pressure from 0.80 atm to 304 mm Hg at constant temperature E. increase the temperature from 400 K to 600 K.
Chem 102, Midterm 1 Version A page 2 of 7 3. Of the following gases, which ONE has the greatest density at standard temperature and pressure? A. CF 4 B. NH 3 C. Ne D. H 2 E. He 4. The addition of 2.0 g He(g) at 25 C to a fixed-volume container of 10.0 L that already contains H 2 (g) at a temperature of 30 C and a pressure of 0.980 atm will: A. have no effect on the final gas pressure in the container B. cause the final pressure in the container to exceed 4 atm C. produce a 40% increase in gas pressure in the container D. bring the final pressure in the container to just slightly less than 2.0 atm E. cause the final pressure in the container to exceed 2 atm 5. If 1.0 L of CO 2 (g) is compared to 1.0 L of H 2 (g), when both samples at a temperature of 25 C and one atmosphere pressure, then: A. the CO 2 and H 2 molecules have the same average speed B. there are more H 2 molecules than there are CO 2 molecules C. the average kinetic energy of the CO 2 molecules is greater than that of the H 2 molecules D. the mass of the one liter sample of CO 2 equals the mass of the one liter sample of H 2 E. the H 2 molecules are, on average, moving more quickly than the CO 2 molecules 6. Which ONE of the following assumptions is NOT used to explain the ideal gas law? A. gas particles themselves occupy a negligible percentage of the total gas volume B. attractive and repulsive forces are negligible in gases C. collisions between gas molecules are perfectly elastic D. at constant temperature, all gas molecules have the same kinetic energy. E. gas molecules are in continuous random motion 7. The reason the stratosphere contains very little dissociated nitrogen (i.e. nitrogen atoms) is: A. Nitrogen atoms are very reactive. They react with other substances immediately upon formation. B. The dissociated nitrogen atoms very rapidly diffuse out of the atmosphere and into space. C. The bond energy of nitrogen (N2) is very large and therefore N2 is difficult to photodissociate. D. Most photodissociation of atmospheric N 2 occurs in the troposphere and not the stratosphere. E. There is no N 2 in the stratosphere.
Chem 102, Midterm 1 Version A page 3 of 7 8. Which of the following molecules can be greenhouse gases? (i) CO 2 (ii) H 2 O (iii) N 2 (iv) Cl 2 (v) H 2 (vi) NO 2 A. i, ii & vi B. i & iv C. i, ii & iii D. i & v E. i & vi 9. Which of the following statements about the atmosphere and atmospheric chemistry is INCORRECT? A. Acidity caused by acid rain can be neutralized by adding limestone, CaCO 3 (s), to lakes. B. The greenhouse effect contributes to maintaining a livable uniform temperature on the Earth s surface. C. Photodissociation involves the removal of an electron from an atom or molecule as a result of the absorption of a photon. D. A key reaction in the production of smog is the photodissociation of NO 2 (g) E. Acidified lakes have elevated concentrations of dissolved Al 3+ ions, which are harmful to fish populations. 10. Which of the following statements are CORRECT? (i) SO 2 is the only gas that contributes to the problem of acid rain. (ii) N 2, O 2, and H 2 O are not greenhouse gases. (iii) One human-caused imbalance is too little ozone in the stratosphere and too much in the troposphere. (iv) O 3 in the atmosphere protects the earth from infrared radiation. (v) The depletion of ozone over Antarctica is seasonal because it requires sunlight A. i, iii, and v B. ii, iii, and iv C. ii, iii and v D. ii and iii E. iii and v 11. Which of the following is a CORRECT statement about a system and its surroundings during an energy exchange? A. The internal energy of the system is the sum of all the potential energies of its components. B. A decrease in the volume of a system means that the internal energy of the system increases. C. A system that releases heat to its surroundings gains internal energy. D. If ΔE system < 0, the internal energy of both the system and the surroundings decreases. E. The surroundings are the part of the universe that is studied.
Chem 102, Midterm 1 Version A page 4 of 7 12. If a reaction is carried out at constant pressure, which of the following statements is correct? A. The reaction is likely to be exothermic. B. The heat change is equal to the enthalpy change. C. The reaction is likely to be endothermic D. The heat change is smaller than the volume change. E. The heat change is equal to the change in temperature. 13. Calculate the change in internal energy for the following situation: A balloon is cooled by removing 0.655 kj of heat. The balloon shrinks, of course, and the atmosphere does 382 J of work on the balloon. ΔE for this process is A. -0.273 kj B. 273 J C. 0.273 kj D. 381 J E. -381 J 14. A gas is confined to a cylinder under a constant atmospheric pressure of 1 atm, as illustrated. The initial volume is 3.0 L and the temperature is 300 K. The gas undergoes a chemical reaction; at the completion of the reaction the final volume is 5.0 L and the final temperature is 310 K. Which of the following statements correctly describes the changes in the system? A. Work was done on the system and ΔH for the reaction is negative. B. Work was done by the system and ΔH for the reaction is positive. C. Work was done by the system and ΔH for the reaction is negative. D. Work was done on the system and ΔH for the reaction is positive. E. Work was done by the system and the sign of ΔH cannot be determined.
Chem 102, Midterm 1 Version A page 5 of 7 Part II written answers to questions: Write your answers directly on this test paper. Show all your work. Hand in the entire test paper at the end of the test period. 8 marks 1. [3](a) A 0.500 m 3 canister contains Freon-12 (CF 2 Cl 2 ) at a pressure of 85.0 kpa at 23 C. What mass of Freon-12 does the canister contain (in kg)? [2] b). Describe briefly, using a chemical equation, the useful function of the earth s stratospheric ozone layer. [3] c) Describe, using chemical equations, how chlorofluorocarbons such as the Freon-12 in part (a) of this problem, contribute to the depletion of the stratospheric ozone layer.
Chem 102, Midterm 1 Version A page 6 of 7 5 marks 2.[3]a) An expandable container of volume 2.35 L is filled with O 2 (g) at 0 C and a pressure of 1 atm. The gas is allowed to expand to a volume of 5.00 L as a result of changes in pressure and temperature. What is the density (in g/l) of the gas in the container under these changed conditions? [2] b). The container from part (a) above is again placed in the initial conditions at 0 C and a pressure of 1 atm, producing a volume of 2.35 L What is the pressure (in atm) in the container if 0.30 mol of argon [ Ar(g)] is added to the container and the temperature and volume are held constant? 4 marks 3. A gas is confined to a cylinder fitted with a piston and an electrical wire as shown below. A current is supplied to the wire so that 137 J of energy is added to the system. Consider two different cases: In Case #1 the piston is allowed to move as the energy is added. In Case #2 the piston is fixed in place and cannot move. Circle the correct response for each question below. a) In which case does the gas sample have the higher temperature after the addition of the 137 J of electrical energy? Case #1 or Case #2 b) In Case #1, which quantity is larger (i.e. larger in magnitude)? q OR w OR There s not enough information to decide. c) In Case #2, which quantity is larger (i.e. larger in magnitude)? q OR w OR There s not enough information to decide. d) The value of ΔE for the system (the confined gas) in the two cases is ΔE (Case #1) > ΔE (Case #2) OR ΔE (Case #1) < ΔE (Case #2) OR ΔE (Case #1) = ΔE (Case #2)
Chem 102, Midterm 1 Version A page 7 of 7 4 marks 4. [2](a) Is the measured pressure of a real gas lower or higher compared to that of an ideal gas? Explain your answer. [2] b). Explain why a volume correction term is needed in the van der Waals equation for a real gas. 3 marks 5. Identify ONE reaction listed to the right that best matches each chemical processes listed on the left. a) Neutralization of acid rain by limestone b) Reaction used to remove the sulfur produced by burning fossil fuels c) Reaction that contributes to photochemical smog d) Reaction involved in the degradation of statues and buildings e) Formation of one component of acid rain f) Dissolution of carbon dioxide in the ocean A. 2 NO(g) + O 2 (g) 2 NO 2 (g) B. CaCO 3 (s) CaO(s) + CO 2 (g) C. SO 3 (g) + H 2 O(l) H 2 SO 4 (aq) D. CaCO 3 (s) + 2 H + (aq) Ca 2+ (aq) + CO 2 (g) + H 2 O(aq) E. CO 2 (g) + H 2 O(l) H 2 CO 3 (aq) F. ClOOCl(g) + uv light 2 Cl(g) + O 2 (g) G. 6 CO 2 (g) + 6 H 2 O(l) plants H. CaO(s) + SO 2 (g) CaSO 3 (s) I. C 6 H 12 O 6 (aq) yeast C 6 H 12 O 6 (aq) + 6 O 2 (g) 2 C 2 H 5 OH(aq) + 2 CO 2 (g) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~THE END~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~