UNIT II - REVIEW EQUILIBRIA. Part I - Multiple Choice. 1. In which of the following does the entropy decrease?

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1 CHEMISTRY 12 UNIT II - REVIEW EQUILIBRIA Part I - Multiple Choice 1. In which of the following does the entropy decrease? A. NaCl (s) Na + (aq) + Cl (aq) B. 4 NO (g) + 6 H 2 O (g) 4 NH 3 (g) + 5 O 2 (g) C. 2 NaHCO 3 (s) Na 2 CO 3 (s) + CO 2 (g) + H 2 O (g) D. CaCO 3 (s) + 2 HCl (aq) CaCl 2 (aq) + CO 2 (g) + H 2 O (l) 2. Consider the following equilibrium: H 2 (g) + CO 2 (g) CO (g) + H 2 O (g) ΔH = + 41 kj The temperature of the above equilibrium system is increased while kept at a constant volume. A new state of equilibrium is established in which there is A. an increase in [ CO] and a decrease in Keq B. an increase in [ CO] and an increase in Keq C. an increase in [CO 2] and a decrease in Keq D. an increase in [CO 2] and an increase in Keq 3. Consider the following equilibrium: 2 SO 3 (g) 2 SO 2 (g) + O 2 (g) The volume of the system is decreased at a constant temperature. A new state of equilibrium is established by a shift of the original equilibrium to the A. left and [SO 3 ] increases. B. right and [SO 3 ] decreases. C. left and [SO 3 ] remains unchanged. D. right and [SO 3 ] remains unchanged. 4. Consider the following equilibrium: 2 H 2 S (g) 2 H 2 (g) + S 2 (g) At equilibrium, [ H 2 S] = mol / L, [H 2 ] = 0.10 mol / L and [ S 2 ] = mol / L. The value of Keq is calculated using the ratio A. (0.10) (0.40) C. (0.50) (0.50) (0.10) (0.50) B. (0.10) 2 (0.40) D. (0.50) 2 (0.50) 2 (0.10) 2 (0.40) 5. Consider the following equilibrium: SO 2 Cl 2 (g) SO 2 (g) + Cl 2 (g) A 1.0 L container is initially filled with 2.0 mol of SO 2 Cl 2. As the reaction proceeds towards equilibrium, the rate of the forward reaction A. increases and the [SO 2 ] increases. B. increases and the [SO 2 ] decreases. C. decreases and the [SO 2 ] increases. D. decreases and the [SO 2 ] decreases.

2 6. Which of the following is true for all equilibrium systems? A. The mass of reactants is equal to the mass of products. B. Addition of a catalyst changes the equilibrium concentrations. C. The concentration of reactants is equal to the concentration of products. D. The rate of the forward reaction is equal to the rate of the reverse reaction. 7. When the temperature of an equilibrium system is increased, the equilibrium always shifts to favour the A. exothermic reaction. B. endothermic reaction. C. formation of products. D. formation of reactants. 8. Consider the following equilibrium: 2 NO (g) + Cl 2 (g) 2 NOCl (g) At constant temperature and volume, Cl 2 is added to the above equilibrium system. As equilibrium reestablishes, the A. Keq will increase. B. Keq will decrease. C. [ NO] will increase. D. [NOCl] will increase. 9. Consider the following equilibrium: N 2 (g) + 3 H 2 (g) 2 NH 3 (g) + 92 kj In which of the following will both changes shift the equilibrium right? A. An increase in volume and a decrease in temperature. B. An increase in volume and an increase in temperature. C. A decrease in volume and a decrease in temperature. D. A decrease in volume and an increase in temperature. 10. Consider the following equilibrium: COCl 2 (g) CO (g) + Cl 2 (g) Keq = For the above system, A. [COCl 2 ] < [CO][Cl 2 ] B. [COCl 2 ] = [CO] [Cl 2 ] C. [COCl 2 ] > [CO] [Cl 2 ] D. [COCl 2 ] = 1 [CO] [Cl 2 ] 11. Consider the following: 2 C (s) + O 2 (g) 2 CO (g) A 1.00 L flask is initially filled with 2.00 mol C and mol O 2. At equilibrium, the [ O 2 ] is mol / L. The Keq value is A B C D. 2.25

3 12. Consider the following: 2 NO 2 (g) N 2 O 4 (g) Keq = A 1.0 L flask is filled with 1.4 mol NO 2 and 2.0 mol N 2 O 4. To reach equilibrium, the reaction proceeds to the A. left as Trial K eq > K eq B. left as Trial K eq < K eq C. right as Trial K eq > K eq D. right as Trial K eq < K eq 13. In an exothermic equilibrium reaction involving only gases, the value of Keq can be decreased by A. adding some reactant gas. B. removing some reactant gas. C. increasing the temperature. D. decreasing the temperature. 14. Consider the following equilibrium: I 2 (s) + H 2 O (l) H + (aq) + I (aq) + HOI (aq) The equilibrium constant expression for the above system is A. K eq = [H + ] [I ] B. K eq = [H + ] [I ] [HOI] C. K eq = [H + ] [I ] [HOI] [I 2] [H 2 O] D. K eq = [H + ] [I ] [HOI] [H 2 O] 15. Consider the following equilibrium: 2 NO (g) + Cl 2 (g) 2 NOCl (g) Keq = 12 At equilibrium, [NOCl] = mol / L and [NO] = mol / L. The [Cl 2 ] is A mol /L B mol /L C mol /L D mol /L

4 CHEMISTRY 12 UNIT II - REVIEW EQUILIBRIA 1. Consider the following equilibrium: 2 CH 4 (g) C 2 H 2 (g) + 3 H 2 (g) A mol sample of CH 4 is added to an empty 1.00 L container. At equilibrium, the [C 2 H 2 ] is mol / L. Calculate the equilibrium constant. (4 marks) 2. Consider the following equilibrium: 2 NOCl (g) 2 NO (g) + Cl 2 (g) A chemist places 2.00 mol NOCl in a 1.0 L container. Describe the changes in [NOCl] and [Cl 2 ] as the system approaches equilibrium. (1 mark) 3. Consider the following equilibrium: 2 NO (g) + O 2 (g) 2 NO 2 (g) Keq = a) Write the Keq expression. (1 mark) b) Explain why the [ NO 2 ] is greater than the [ NO] at equilibrium when the [ O 2 ] is 1. 0 mol / L. (1 mark)

5 4. Consider the following equilibrium: 2 HI (g) H 2 (g) + I 2 (g) K eq = A 1.00 L container is initially filled with 4.00 mol HI. Calculate the [HI] at equilibrium. (4 marks)