AP Chemistry Name :

Worksheet : Chapter 6 ; obj. 1-18-2 Date :

_____ 1. For the boiling of water (system) which of the following are true?

I. The kinetic energy of the system increases.

II. The kinetic energy of the surroundings increases.

III. The potential energy of the system decreases.

IV. The process is endothermic.

V. The process is exothermic.

a. I only b. I and II c. I and IV d. II and IV e. II and V

_____ 2. Which of the following are not state functions?

I. Work

II. Enthalpy

III. Energy

IV. Heat

V. Entropy

a. I and IV b. I only c. II and III d. II, III and V e. all of the above

_____ 3. Which of the following are true for an endothermic process?

I. Enthalpy of the surroundings increases.

II. Enthalpy of the system decreases.

III. ΔH of the system is negative

IV ΔH of the surroundings is positive.

V. The energy of the universe remains constant.

a. I and II b. I and III c. I, III and IV d. II and IV e. IV and V f. V only

_____ 4. Which of the following will have a negative ΔH?

I. burning log

II. freezing water

III. boiling water

IV. melting ice.

V. the formation of a crystal from its gaseous ions

a. I, III and IV b. III and IV c. I, II and V d. III, IV and V e. none of the above.

_____ 5. In which of the following will the system have a positive ΔE (assume no heat change)?

a. the expansion of a gas b. the compression of a gas.

_____ 6. (T/F) When a gas expands the potential energy of the surroundings decreases.

_____ 7. (T/F) The reaction MgO(s) ↔ Mg(s) + ½O2(g) , ΔH = 601.70 kJ favors the reactants.

_____ 8. For the reaction Li+(g) + Cl-(g) à LiCl(s)

I. ΔH system is positive

II. ΔH surroundings is positive

III. the potential energy of the system increases.

IV. the potential energy of the surroundings increases

V. the reaction is endothermic

a. I, III and V b. II and IV c. II and III d. I, III and IV e. I, II and IV

______9. At which of the following shapes would the carbon dioxide molecule have the lowest potential energy?

a. linear b. bent triatomic

10. Calculate the kinetic energy of an electron (mass = 9.10938291× 10−31 kg) with a velocity of 98.00% of the speed of light (3.00 x 108 m/s).(KE = ½ mv2, mass in kg)

11. What is the potential energy of a 4.40 ton boulder sitting on a cliff that is 40. m high?(1 ton = 2,000 lb, 1 kg = 2.205 lb)(PE = mgz ; mass in kg, g = 9.8m/s2, z = distance in meters)

12. Calculate the ΔE for each of the following.

a. q = +35 kJ ; w = -42 kJ

b. q = -35 kJ; w = +27 kJ

c. In which of the above does the system do work on the surroundings?

13. The volume of an ideal gas is increased from 5.0 L to 45.0 L at a constant pressure of 1.5 atm while absorbing 12.0 kJ of heat energy. Calculate ΔE in kJ.

14. One mole of water at 1.00 atm and 100. ºC has a volume of 30.6 L. When one mole of H2O(g) is condensed to one mole of H2O(l) at 1.00 atm and 100. ºC 40.66 kJ of heat are released. If the density of water(l) at this temperature and pressure is 0.966 g/cm3, calculate the ΔE for the condensation of 64.00 g of water at 1.00 atm and 100. ºC.

_____ 15. (T/F) The ΔH for the chemical reaction involved in cellular respiration will be positive.

_____ 16. (T/F) Cellular respiration is endothermic.

_____ 17. Which of the following is true for the reaction H2SO4(aq) à SO3(g) + H2O(l) (ΔH = 227 kJ)?

I. The reaction is endothermic.

II. The reaction is exothermic.

III. The enthalpy of the surroundings increases.

IV. The kinetic energy of the system decreases.

V. The system works on the surroundings.

a. I and V b. II and III c. II, III and IV d. III and V e. II, III and V

_____ 18. Which of the following are endothermic?

I. When NaOH is dissolved in water, the solution gets warmer.

II. Ice is melted.

III. When sodium carbonate reacts with HCl the solution gets colder.

IV. Water is frozen.

V. C2H5OH(g) à C2H5OH (l)

a. I and IV b. II and III c. II, III and IV d. II, III and V e. none of the above

_____ 19. Which of the following are endothermic? (Hint bond breaking is endothermic).

I. H2 (g)à 2H(g)

II. I2 (g) à I2 (s)

III. Br2 (l) à Br2 (g)

IV. H2O(l) à H2O (s)

V. 2C6H6(g) + 15O2 (g) à 12CO2(g) + 6H2O(g)

a. I and IV b. I and III c. II, IV and V d. II, III and V e. none of the above

20. Write the reaction for the combustion of octane (C8H18)(∆H = -5460 kJ/mol)

a. How much heat is released or absorbed when 88.0 grams of octane are burned in the presence of 216 L of oxygen at 758 mm Hg and a temperature of 20.0 ºC?

Answers to selected problems : 10. 3.94 x10-14 kJ 11. 1.6 x 103 kJ 13. 6.0 kJ 14. -133.4 kJ 20. 3,910 kJ