Question 4. Calculate q when 0.10 g of ice is cooled from 10.ºC to -75ºC. (c ice = J/g ºC) A) -18 J B) -14 J C) -8.5 J D) + 14 J E) +18 J 5-4

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1 Question 1 A system conducts 1.07 kj of heat to the surroundings while delivering 1.79 kj of work. What is the change in internal energy of the system? A) kj B) kj C) kj D) kj 5-1

2 Question 2 Which of the following is endothermic? A) freezing of water B) boiling of water C) reaction between an acid and a base D) a person running E) heating with a furnace 5-2

3 Question 3 In which of the following would ΔH be less than (more negative) than ΔU of the system? A) An ideal gas is cooled at constant pressure. B) A mixture of gases undergoes an exothermic reaction in a container of fixed volume C) A solid yields a mixture of gases in an exothermic reaction that takes place in a container of variable volume. 5-3

4 Question 4 Calculate q when 0.10 g of ice is cooled from 10.ºC to -75ºC. (c ice = J/g ºC) A) -18 J B) -14 J C) -8.5 J D) + 14 J E) +18 J 5-4

5 Question An unknown volume of water at 18.2ºC is added to 24.4 ml of water at 35.0ºC. If the final temperature is 23.5ºC, what was the unknown volume? (Assume that no heat is lost to the surroundings; d water = 1.00 g/ml) A) 16.7 ml B) 22.4 ml C) 596 ml D) 53 ml E) cannot be determined with information provided

6 Question 6 Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars every day. Although the actual process also requires water, a simplified equation (with rust shown as Fe 2 O 3 ) is given. What mass of rust forms when 49.3 kj of heat is released? 4Fe (s) + 3O 2 (g) Fe 2 O 3 (s) r H = kj/mol A) g B) 223 g C) 9.54 g D) 3300 g E) 825 g 5-6

7 Question 7 Given the following reactions, calculate Δ r H for: Ca (s) + ½O 2 (g) + CO 2 (g) CaCO 3 (s) 1. Ca (s) + ½O 2 (g) CaO (s) ΔH = kj 2. CaCO 3 (s) CaO (s) + CO 2 (g) ΔH =178.3 kj 5-7 A) kj B) kj C) kj D) kj E) kj

8 Question 8 Calculate Δ r H 0 for the BALANCED reaction, CH 4 (g) + Cl 2 (g) CCl 4 (l) + HCl (g) [unbalanced] 5-8 given Δ f H 0 HCl (g) = kj/mol Δ f H 0 CH 4 (g) = kj/mol Δ f H 0 CCl 4 (l) = -139 kj/mol A) -433 kj B) -156 kj C) -583 kj D) -306 kj E) Cannot determine with information given

9 Question 9 For each of the following events, the system is in parenthesis. In which situation is heat transferred out of the system and work done on the system? A) You pump air into an automobile (tire). B) A (tree) rots in a forest. C) You strike a (match). D) You cool juice in an (ice chest). E) You cook (food) on a kitchen range. 5-9

10 Question 10 When ΔH is negative, which of the following is correct in terms of the heat exchanged? A) The heat is a reactant. B) The heat is a product. C) The heat is neither a reactant nor product. D) The heat is both a reactant and a product. 5-10

11 Question 11 A system that does no work but which transfers heat to the surroundings has A) q < 0, ΔU > 0. B) q < 0, ΔU < 0. C) q > 0, ΔU > 0. D) q > 0, ΔU < 0. E) q < 0, ΔU =

12 Question 12 Which one of the following relationships is always correct? A) potential energy + kinetic energy = constant B) U = q + w C) ΔU = ΔH - PΔV D) H = U + PV E) ΔH = q v 5-12

13 Question 13 The temperature of a cold pack is lowered when NH 4 NO 3 dissolves in water. Which of the following is true of this reaction? A) ΔH < 0, process is exothermic B) ΔH > 0, process is exothermic C) ΔH < 0, process is endothermic D) ΔH > 0, process is endothermic E) ΔH = 0, since cold packs are sealed 5-13

14 Question 14 If you wished to warm your room using an object heated to 100 C on top of a stove, which of the following 6.8 kg objects would be your best choice? A) iron, heat capacity = J/g K B) copper, heat capacity = J/g K C) granite, heat capacity = 0.79 J/g K D) gold, heat capacity = J/g K E) water, heat capacity = 4.18 J/g K 5-14

15 Question 15 Which one of the following statements about standard states is incorrect? A) The standard state of a solid compound is the pure solid. B) The standard state of a liquid compound is the pure liquid. C) The standard state of a gaseous compound is the gas at a pressure of 1 bar. D) The standard state of an aqueous solute is a saturated solution in water. 5-15

16 Question 16 Which one of the following is not a correct formation reaction? A) H 2 (g) + O (g) H 2 O (l) B) 1/2 H 2 (g) + 1/2 Cl 2 (g) HCl (g) C) 6 C (s, graphite) + 3 H 2 (g) C 6 H 6 (l) D) C (s, graphite) C(s, diamond) E) 6 C (s, graphite) + 6 H 2 (g) + 3O 2 (g) C 6 H 12 O 6 (s) 5-16

17 Question 17 Ca(OH) 2 + CO 2 CaCO 3 + H 2 O ΔH = kj What amount of heat is released when 3.76 moles of Ca(OH) 2 react. A) -18 kj B) -69 kj C) -2.6 x 10 2 kj D) 2.6 x 10 2 kj 5-17

18 Question 18 Which one of the following is not in its most stable form at 25 C and 1 bar pressure? A) Co (s) B) Br 2 (l) C) N 2 (g) D) F 2 (s) 5-18

19 Question 19 Given that 2 Al + Fe 2 O 3 2 Fe + Al 2 O 3 ΔH = -850 kj what is the ΔH for 2 Fe + Al 2 O 3 2 Al + Fe 2 O 3? A) -850 kj B) -425 kj C) +850 kj D) +425 kj 5-19

20 Question 20 Given that 2 Al + Fe 2 O 3 2 Fe + Al 2 O 3 ΔH = -850 kj What is the ΔH for 4 Fe + 2 Al 2 O 3 4 Al + 2 Fe 2 O 3? A) kj B) kj C) -425 kj D) +425 kj 5-20

21 Answer Key Chapter 5 1. D 2. B 3. A 4. A 5. D 6. C 7. E 8. A 9. C 10. B 11. B 12. D 13. D 14. E 15. D 16. A 17. D 18. D 19. C 20. B