Chem1405 homework of chap8
1.In the reaction the rate of disappearance of hydrogen was 0.60 mol/ min. What was the rate of
disappearance of nitrogen? 3 H2( g)+ N2( g)2 NH3( g)
(A)0.60 mol/min
(B)0.40 mol/min
(C)0.20mol/min
(D)0.10 mol/min
2. The heat of a reaction, ΔHrxn , is 12 kJ, and the activation energy of the forward reaction, E forward, is -46
kJ. Calculate the activation energy of the reverse reaction, E back .
(A)-58 kJ
(B)58 kJ
(C)-34kJ
(D)12kJ
3. A reaction that evolves heat as products are produced is referred to as (Section 8.2)
a. endothermic.
b. exothermic.
c. activated.
4. Which of the following statements about a catalyst in a chemical reaction is NOT true? (Section 8.3)
a. It is regenerated at the end of the chemical reaction.
b. It increases the rate of a reaction.
c. It ensures that the maximum amount of product that can be formed in a chemical reaction is formed.
5. Which of the following statements about chemical equilibrium is true? (Section 8.5)
a. At chemical equilibrium, all chemical reactions have stopped.
b. At chemical equilibrium, the rate of the forward chemical reaction is equal to the rate of the reverse
chemical reaction.
c. At chemical equilibrium, all reactants in the chemical reaction have been depleted.
6. Which of the following formulas represents the equilibrium constant for the formation of ammonia
gas, N2(g) + 3H2(g)  2NH3(g)? (Section 8.6)
a. [NH3]2/[N2][H2]3
b. [NH3]/[N2][H2]3
c. [N2][H2]3/[NH3]2
7. Write the equilibrium- constant expressions for reactions:
(A) [CO2] 8 [H2O]8 /[C8H16][O2]12
(B) [C8H16][O2]12 / [CO2] 8 [H2O]8
(C) [CO2] 8 [H2O]8 /[O2]12
(D) [CO2] [H2O] /[C8H16][O2]
8. The equilibrium constant for the dissociation of lactic acid into lactate, lactic acid lactate + H+ is 1.4
×10-4. What does this value reveal about the concentrations of reactants and products at equilibrium?
(Section 8.6)
a. There are more products present at equilibrium.
b. There are more reactants at equilibrium.
c. The amounts of products and reactants are equal.
9. In the chlorination of ethane, C2H6(g) + Cl2(g)  C2H5Cl(s) + HCl(g), the equilibrium concentrations at
10°C are [C2H6] = 1.71 M, [Cl2] = 1.71 M, and [HCl] = 0.29 M. Calculate the equilibrium constant for the
chlorination of ethane at 10°C. (Section 8.6)
a. 0.17 b. 10. c. 0.10
10. In the reaction of hydrogen gas and iodine gas to form hydrogen iodide, H2(g) + I2(g) 2HI(g), what
would be the affect on the equilibrium if I2 were removed from the reaction? (Section 8.8)
a. The reaction would shift toward the production of reactants.
b. The reaction would shift toward the production of products.
c. There would be no effect on the equilibrium.
11. The reaction of sulfur dioxide and oxygen to produce sulfur trioxide, 2SO2(g) + O2(g)  2SO3(g), is
exothermic. What would be the effect on the equilibrium if the temperature of the reaction were
decreased? (Section 8.8)
a. The reaction would shift toward the production of reactants.
b. The reaction would shift toward the production of products.
c. There would be no effect on the equilibrium.