TEST TEMA 8 QUÍMICA

1) At equilibrium, __________. A) all chemical reactions have ceased. B) the rates of the forward and reverse reactions are equal. C) the rate constants of the forward and reverse reactions are equal. D) the value of the equilibrium constant is 1. E) the limiting reagent has been consumed.

5) Which one of the following will change the value of an equilibrium constant?. A) changing temperature. B) adding other substances that do not react with any of the species involved in the equilibrium. C) varying the initial concentrations of reactants. D) varying the initial concentrations of products. E) changing the volume of the reaction vessel.

6) Which of the following expressions is the correct equilibrium-constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide? N2O4 (g) 2NO2 (g). A) ["N" "O" _2 ]/[N_2 O_4 ]. B) ["N" "O" _2 ]^2/[N_2 O_4 ]. C) ["N" "O" _2 ]/[N_2 O_4 ]^2. D) [NO2][N2O4]. E) [NO2]2[N2O4].

7) Which of the following expressions is the correct equilibrium-constant expression for the following reaction? CO2 (g) + 2H2 (g) CH3OH (g). A) ["C" "H" _3 "OH" ]/["C" "O" _2 ]. B) ["C" "H" _3 "OH" ]/["C" "O" _2 ][H_2 ]. C) (["C" "O" _2 ] [H_2 ]^2)/["C" "H" _3 "OH" ]. D) ["C" "O" _2 ][H_2 ]/["C" "H" _3 "OH" ]. E) ["C" "H" _3 "OH" ]/(["C" "O" _2 ] [H_2 ]^2 ).

8) The equilibrium-constant expression depends on the __________ of the reaction. A) stoichiometry. B) mechanism. C) stoichiometry and mechanism. D) the quantities of reactants and products initially present. E) temperature.

9) The equilibrium constant for reaction 1 is K. The equilibrium constant for reaction 2 is __________. (1) SO2 (g) + (1/2) O2 (g) SO3 (g) (2) 2SO3 (g) 2SO2 (g) + O2 (g). A) K2. B) 2K. C) 1/2K. D) 1/K2. E) -K2.

10) The value of Keq for the following reaction is 0.25: SO2 (g) + NO2 (g) SO3 (g) + NO (g) The value of Keq at the same temperature for the reaction below is __________. 2SO2 (g) + 2NO2 (g) 2SO3 (g) + 2NO (g). A) 0.50. B) 0.063. C) 0.12. D) 0.25. E) 16.

13) The Keq for the equilibrium below is 7.52 × 10-2 at 480.0°C. 2Cl2 (g) + 2H2O (g) 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 4HCl (g) + O2 (g) 2Cl2 (g) + 2H2O (g). A) 0.0752. B) -0.0752. C) 13.3. D) 5.66 × 10-3. E) 0.150.

14) The Keq for the equilibrium below is 5.4 × 1013 at 480.0°C. 2NO (g) + O2 (g) 2NO2 (g) What is the value of Keq at this temperature for the following reaction? 4NO (g) + 2O2 (g) 4NO2 (g). A) 5.4 × 1013. B) 5.4 × 10-13. C) 1.9 × 1012. D) 1.9 × 10-12. E) 2.9 × 1027.

15) The Keq for the equilibrium below is 7.52 × 10-2 at 480.0°C. 2Cl2 (g) + 2H2O (g) 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 2HCl (g) + O2 (g) Cl2 (g) + H2O (g). A) 13.3. B) 3.65. C) -0.0376. D) 5.66 × 10-3. E) 0.274.

16) The Keq for the equilibrium below is 5.4 × 1013 at 480.0°C. 2NO (g) + O2 (g) 2NO2 (g) What is the value of Keq at this temperature for the following reaction? NO2 (g) NO (g) + 1/2 O2 (g). A) 5.4 × 10-13. B) 5.4 × 1013. C) 1.4 × 10-7. D) 5.66 × 10-3. E) none of the above.

20) Given the following reaction at equilibrium, if Kc = 1.90 × 1019 at 25.0°C, Kp = __________. H2 (g) + Br2 (g) 2 HBr (g). A) 5.26 × 10-20. B) 1.56 × 104. C) 6.44 × 105. D) 1.90 × 1019. E) none of the above.