1. General Chemistry Principles & Modern Applications 9 th Edition Petrucci/Harwood/Herring/Madura Chapter 7 Thermochemistry Dr. Travis D. Fridgen Memorial University of Newfoundland © 2007 Pearson Education

2. When heat is absorbed by ice (the system) it melts. The quantity q for the system is 1. positive. 2. negative. 3. 0

3. When heat is absorbed by ice (the system) it melts. The quantity q for the system is 1. positive. 2. negative. 3. 0

4. When potassium chlorate decomposes it produces oxygen gas. From the system’s point of view (which is the convention), w is 1. positive. 2. negative. 3. No work done.

5. 1. positive. 2. negative. 3. No work done. When potassium chlorate decomposes it produces oxygen gas. From the system’s point of view (which is the convention), w is

6. Heat is added to the container below while being allowed to expand freely against atmospheric pressure. The temperature and pressure, however, remain constant before and after.  U is, 1. positive. 2. negative. 3. 0

7. Heat is added to the container below while being allowed to expand freely against atmospheric pressure. The temperature and pressure, however, remain constant before and after.  U is, 1. positive. 2. negative. 3. 0

8. The volume of the Atlantic Ocean is about 300 km 3. Without the use of a calculator, estimate the heat that is required to raise the temperature of the Atlantic Ocean by 1 o C (assume the density of water is 1 g cm -3 and the specific heat is 4 J g -1 o C -1. 4. ~10 18 J 1. ~10 3 J 2. ~10 6 J 3. ~10 12 J 5. ~10 25 J

9. The volume of the Atlantic Ocean is about 300 km 3. Without the use of a calculator, estimate the heat that is required to raise the temperature of the Atlantic Ocean by 1 o C (assume the density of water is 1 g cm -3 and the specific heat is 4 J g -1 o C -1. 4. ~10 18 J 1. ~10 3 J 2. ~10 6 J 3. ~10 12 J 5. ~10 25 J

10. In 1 minute the sun shines about 40 kJ m -2 of energy on Earth’s surface and about 10 18 J is required to raise the temperature of the Atlantic by 1 o C. Assuming that all of the sun’s energy is absorbed, how long must the sun shine 1. 4x10 21 min 2. 2.5x10 11 min 3. 2.5x10 5 min 4. 2.5x10 -5 min 5. 4x10 -10 min Where does the energy come from to heat the ocean? on the Atlantic to raise its temperature by 1 o C? The area of the Atlantic ocean is about 100 km 2.

11. In 1 minute the sun shines about 40 kJ m -2 of energy on Earth’s surface and about 10 18 J is required to raise the temperature of the Atlantic by 1 o C. Assuming that all of the sun’s energy is absorbed, how long must the sun shine 1. 4x10 21 min 2. 2.5x10 11 min 3. 2.5x10 5 min 4. 2.5x10 -5 min 5. 4x10 -10 min Where does the energy come from to heat the ocean? on the Atlantic to raise its temperature by 1 o C? The area of the Atlantic ocean is about 100 km 2.

12. You take two frozen steaks and put them into room temperature water for a few hours to thaw. The heat gained by the steak (system) equals the heat lost by the water (surroundings). The best equation to express this, where subscript ‘s’ refers to steak and the subscript w refers to the water, is,

14. 200 g Te (100 o C) 100 g H 2 O 25 o C 50 o C What is the heat capacity of Tellurium? Use 4 J g -1 o C -1 for the heat capacity of water. 1. 0.5 J g -1 o C -1 2. 1 J g -1 o C -1 3. 2 J g -1 o C -1 4. 4 J g -1 o C -1 5. 10 J g -1 o C -1

15. 200 g Te (100 o C) 100 g H 2 O 25 o C 50 o C What is the heat capacity of Tellurium? Use 4 J g -1 o C -1 for the heat capacity of water. 1. 0.5 J g -1 o C -1 2. 1 J g -1 o C -1 3. 2 J g -1 o C -1 4. 4 J g -1 o C -1 5. 10 J g -1 o C -1

16. q P = 250 kJ T=300 K V 2 = 0.110 m 3 1x10 5 Pa Determine  H and  U for the reaction and conditions depicted below. Note: 1 Pa = 1 N m -2. 1. 250 kJ, 251 kJ HH UU 2. 250 kJ, 249 kJ 3. -250 kJ, -251 kJ 4. -250 kJ, -249 kJ 5. -250 kJ, -250 kJ V 1 = 0.120 m 3

17. q P = 250 kJ T=300 K V 2 = 0.110 m 3 1x10 5 Pa Determine  H and  U for the reaction and conditions depicted below. Note: 1 Pa = 1 N m -2. 1. 250 kJ, 251 kJ HH UU 2. 250 kJ, 249 kJ 3. -250 kJ, -251 kJ 4. -250 kJ, -249 kJ 5. -250 kJ, -250 kJ V 1 = 0.120 m 3

18. Ice (the system) melting is 1. an exothermic process. 2. an endothermic process. 3.neither exothermic nor endothermic since the temperature of the system remains constant (0 o C at 1 atm). Note: a bit tricky perhaps until chapter 13.

19. Ice (the system) melting is 1. an exothermic process. 2. an endothermic process. 3.neither exothermic nor endothermic since the temperature of the system remains constant (0 o C at 1 atm). Note: a bit tricky perhaps until chapter 13.

20. The equation for the combustion of butane is, Which one of the following generates the least heat? 1. Burning one mole of butane in excess oxygen. 2. Reacting one mole of oxygen with excess butane. 3. Producing one mole of carbon dioxide by burning butane. 4. Producing one mole of water by burning butane. 5. Burning 0.25 moles of butane with excess oxygen.

21. The equation for the combustion of butane is, Which one of the following generates the least heat? 1. Burning one mole of butane in excess oxygen. 2. Reacting one mole of oxygen with excess butane. 3. Producing one mole of carbon dioxide by burning butane. 4. Producing one mole of water by burning butane. 5. Burning 0.25 moles of butane with excess oxygen.

22. The chemical reaction representing aerobic respiration is, and is the reverse of photosynthesis. This reaction is exothermic by ~2500 kJ per mole of glucose. A small child exhales about 3 moles of CO 2 in a 24 hour period, what is the energy change associated with the photosynthesis reaction required to convert this amount of CO 2 back to glucose? 1. 5000 kJ 2. -5000 kJ 3. -2500 kJ 4. 1250 kJ 5. -1250 kJ

23. The chemical reaction representing aerobic respiration is, and is the reverse of photosynthesis. This reaction is exothermic by ~2500 kJ per mole of glucose. A small child exhales about 3 moles of CO 2 in a 24 hour period, what is the energy change associated with the photosynthesis reaction required to convert this amount of CO 2 back to glucose? 1. 5000 kJ 2. -5000 kJ 3. -2500 kJ 4. 1250 kJ 5. -1250 kJ

24. Given the heats of formation of the potential products of the Ostwald process, which reaction is most exothermic?  H / kJ mol -1 N2N2 0 N2ON2O82.1 NO90.2 NO 2 33.2

25.  H / kJ mol -1 N2N2 0 N2ON2O82.1 NO90.2 NO 2 33.2 Given the heats of formation of the potential products of the Ostwald process, which reaction is most exothermic?

26.  H / kJ mol -1 N2N2 0 N2ON2O82.1 NO90.2 NO 2 33.2 Given the heats of formation of the potential products of the Ostwald process, which reaction is most exothermic?

27.  H / kJ mol -1 N2N2 0 N2ON2O82.1 NO90.2 NO 2 33.2 Given the heats of formation of the potential products of the Ostwald process, which reaction is most exothermic?

28. The equations for the complete and incomplete combustion of octane are given below.  H f / kJ mol -1 CO-111 CO 2 -394 Which reaction is more exothermic and by how much? 1. Incomplete by 283 kJ mol -1. 2. Incomplete by 2264 kJ mol -1. 3. Complete by 2264 kJ mol -1. 4. Complete by 283 kJ mol -1. 5. Complete by 505 kJ mol -1.

29. The equations for the complete and incomplete combustion of octane are given below.  H f / kJ mol -1 CO-111 CO 2 -394 Which reaction is more exothermic and by how much? 1. Incomplete by 283 kJ mol -1. 2. Incomplete by 2264 kJ mol -1. 3. Complete by 2264 kJ mol -1. 4. Complete by 283 kJ mol -1. 5. Complete by 505 kJ mol -1.

30. Two equations incomplete combustion of butane are given below. Given that the heat of formation of CO(g) is -111 kJ mol -1, which reaction is more exothermic and by how much? 1. Reaction A by 111 kJ mol -1. 2. Reaction B by 111 kJ mol -1. 3. Reaction A by 444 kJ mol -1. 4. Reaction B by 444 kJ mol -1. 5. Not enough information to answer.  H f = -111 kJ mol -1

31. Two equations incomplete combustion of butane are given below. Given that the heat of formation of CO(g) is -111 kJ mol -1, which reaction is more exothermic and by how much? 1. Reaction A by 111 kJ mol -1. 2. Reaction B by 111 kJ mol -1. 3. Reaction A by 444 kJ mol -1. 4. Reaction B by 444 kJ mol -1. 5. Not enough information to answer.  H f = -111 kJ mol -1

32. + Given the bond energies below, estimate the enthalpy change for the addition of Br across the double bond in ethene. C—C 350 kJ mol -1 C=C 600 kJ mol -1 C—Br 300 kJ mol -1 Br—Br 200 kJ mol -1 1. 150 kJ 2. -150 kJ 3. 220 kJ 4. -220 kJ 5. Not enough data to determine  r H

33. + Given the bond energies below, estimate the enthalpy change for the addition of Br across the double bond in ethene. C—C 350 kJ mol -1 C=C 600 kJ mol -1 C—Br 300 kJ mol -1 Br—Br 200 kJ mol -1 1. 150 kJ 2. -150 kJ 3. 220 kJ 4. -220 kJ 5. Not enough data to determine  r H