A) 1.78 104 J/g oC. B) 2.22 J/g oC. C) 0.234 J/g oC. D) 0.450 J/g oC. E) 0.158 J/g oC. 4. Which of the following is a valid unit for specific heat (or specific heat ...
2. A 5.10-g sample of iron is heated from 36.0oC to 75.0oC. The amount of energy required is 89.46 J. The specific heat capacity of this sample of iron is A) 1.78 × 104 J/g oC B) 2.22 J/g oC C) 0.234 J/g oC D) 0.450 J/g oC E) 0.158 J/g oC
4. Which of the following is a valid unit for specific heat (or specific heat capacity)? A) cal/g °C B) cal C) cal/g D) °C E) g °C/cal
6. Calculate the heat given off when 155.5 g of copper cools from 155.0oC to 23.0oC. The specific heat capacity of copper is 0.385 J/g oC. A) 1.38 × 103 J B) 9.28 × 103 J C) 5.33 × 104 J D) 7.90 × 103 J E) none of these
9. The specific heat capacity of iron is 0.45 J/g oC. How many joules of energy are needed to warm 1.93 g of iron from 20.00oC to 29.00oC? A) 25 J B) 17 J C) 39 J D) 16 J E) 7.8 J
10. How many joules of energy would be required to heat 29.6 g of carbon from 23.6oC to 54.2oC? (Specific heat capacity of carbon = 0.71 J/goC.) A) 6.4 × 102 J B) 1.7 × 103 J C) 1.1 × 103 J D) 1.3 × 103 J E) none of these
13. Assume that 462.0 J of heat is added to 5.00 g of water originally at 23.0oC. What would be the final temperature of the water? (Specific heat capacity of water = 4.184 J/goC.) A) 22.1 oC B) 60.1 oC C) 73.1 oC D) 45.1 oC E) none of these
17. Calculate [pic]E given the following information: q = +41 kJ, w = +24 kJ A) 17 kJ B) 65 kJ C) –65 kJ D) –17 kJ E) 1.7 kJ
19. [pic]E for a system is 31 kJ. If 175 kJ of work was done on the system, how much heat was released? A) 144 kJ B) 206 kJ C) –206 kJ D) –144 kJ E) –5.6 kJ
20. 2105.34 J of energy is equivalent to how many calories? A) 1.98733 [pic] 10–3 cal B) 0.503188 cal C) 2.10534 cal D) 2109.52 cal E) 503.188 cal
23. Express 3.16 [pic] 105 J in kilocalories. A) 1.32 [pic] 106 kcal B) 7.55 [pic] 104 kcal C) 75.5 kcal D) 316 kcal E) 1.32 [pic] 103 kcal
25. Perform the indicated conversion: 1.359 kcal = _______________ J A) 5.686 [pic] 103 J B) 5.686 J C) 5.686 [pic] 10–3 J D) 324.8 J E) 3.079 J
27. Perform the indicated conversion: 3.16 [pic] 103 cal = _______________ J A) 755 J B) 1.32 [pic] 104 J C) 13.2 J D) 7.55 [pic] 105 J E) 1.32 [pic] 10–3 J
28. Determine the enthalpy change when 23.5 g of carbon is reacted with oxygen according to the reaction C(s) + O2(g) [pic] CO2(g) [pic]H = –394 kJ/mol A) 771 kJ B) 9.26 [pic] 103 kJ C) –771 kJ D) –9.26 kJ E) 8.19 kJ
29. For the reaction H2(g) + [pic]O2(g) [pic] H2O(l) [pic]H = –286 kJ/mol Calculate the enthalpy change when 5.37 g of hydrogen gas is reacted with excess oxygen. A) –53.3 kJ B) 762 kJ C) –762 kJ D) 1.54 [pic] 103 kJ E) –1.54 [pic] 103 kJ
30. For the reaction H2(g) + [pic]O2(g) [pic] H2O(l) [pic]H = –286 kJ/mol What is the enthalpy change when 17.5 mol of hydrogen gas reacts with excess oxygen? A) 16.3 kJ B) –16.3 kJ C) 6.12 [pic] 10–2 kJ D) –5.01 [pic] 103 kJ E) –2.48 [pic] 103 kJ
31. For the reaction H2(g) + [pic]O2(g) [pic] H2O(l) [pic]H = –286 kJ/mol Calculate the enthalpy change when 2.82 g of water is produced. A) 101 kJ B) 807 kJ C) –807 kJ D) 44.8 kJ E) –44.8 kJ
32. A 100.0-g sample of water at 27.0oC is poured into a 71.5-g sample of water at 89.0oC. What will be the final temperature of the water?[pic] A) 85.8oC B) 318oC C) 21.4oC D) 129oC E) 52.8oC
34. The specific heat capacity of gold is 0.13 J/goC. How many calories of energy are needed to warm 0.767 g of gold from 30.0oC to 39.5oC? A) 0.95 cal B) 0.23 cal C) 1.7 cal D) 4.0 cal E) 30 cal
37. Which of the following statements about energy is false? A) A reaction cannot be exothermic overall if activation energy is required. B) A system is the most stable when it is at its lowest energy state. C) Energy can be defined as whatever is required to oppose a natural tendency. D) Energy transferred into a system can also be transferred out of the system. E) An atom in an excited state can return to its ground state by releasing visible light.
38. Which of the following processes is exothermic? A) rolling a ball up a hill B) boiling water in a beaker to make steam C) allowing meat to thaw after taking it out of the freezer D) reacting hydrogen and oxygen gases to make water E) a popsicle melting on a warm summer day
39. __________ is the ability to do work or produce heat. A) Gravity B) Temperature C) Radiation D) Matter E) Energy
40. True or false? The law of conservation of energy states that energy can be converted from one form to another but can be neither created nor destroyed. A) True B) False
43. __________ is a measure of the random motions of the components of a substance. A) Heat B) Temperature C) Energy D) Radiation E) Matter
49. On a cold winter day, a steel metal fence post feels colder than a wooden fence post of identical size because A) the specific heat capacity of steel is higher than the specific heat capacity of wood. B) the specific heat capacity of steel is lower than the specific heat capacity of wood. C) steel has the ability to resist a temperature change better than wood. D) the mass of steel is less than wood, so it loses heat faster. E) Two of the above statements are true.
50. According to the first law of thermodynamics, the energy of the universe is constant. Does this mean that ΔE is always equal to zero? A) Yes, ΔE = 0 at all times, which is why q = -w. B) No, ΔE does not always equal zero, but this is due only to factors such as friction and heat. C) No, ΔE does not always equal zero because it refers to the system’s internal energy, which is affected by heat and work. D) No, ΔE never equals zero because work is always being done on the system or by the system. E) No, ΔE never equals zero because energy is always flowing between the system and surroundings.
53. True or false? Enthalpy is not a state function. A) True B) False
54. Consider the following reaction: ClF + F2 [pic] ClF3; [pic]H = -108.7 kJ/mol Is the reaction exothermic or endothermic? A) exothermic B) endothermic
2. Ans: D 4. Ans: A 6. Ans: D 9. Ans: E 10. Ans: A 13. Ans: D 17. Ans: B 19. Ans: D 20. Ans: E 23. Ans: C 25. Ans: A 27. Ans: B 28. Ans: C 29. Ans: C 30. Ans: D 31. Ans: E 32. Ans: E 34. Ans: B 37. Ans: A 38. Ans: D 39. Ans: E 40. Ans: A 43. Ans: B 49. Ans: B 50. Ans: C 53. Ans: B 54. Ans: A