MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The effect of a catalyst on a chemical reaction is to. A) increase the entropy change associated with a reaction B) make reactions more exothermic C) accelerate the forward reaction only D) lower the energy of the transition state E) react with product, effectively removing it and shifting the equilibrium to the right 2) What is the ph of an aqueous solution at 25eC in which [OH-] is M? A) B) C) D) E) ) What is the concentration (in M) of hydroxide ions in a solution at 25eC with ph = 4.282? A) B) 9.72 C) 4.28 D) E) ) Consider the following reaction at equilibrium: 2CO2 (g) 2CO (g) + O2 (g) DHe = -514 kj Le Cha^telier's principle predicts that an increase in temperature will. A) decrease the value of the equilibrium constant B) increase the value of the equilibrium constant C) decrease the partial pressure of CO2 (g) D) increase the partial pressure of CO E) increase the partial pressure of O2 (g) 5) Consider the following reaction at equilibrium: 2NH3 (g) N2 (g) + 3H2 (g) DHe = kj Le Cha^telier's principle predicts that adding N 2 (g) to the system at equilibrium will result in. A) a decrease in the concentration of H2 (g) B) a lower partial pressure of N2 C) an increase in the value of the equilibrium constant D) a decrease in the concentration of NH3 (g) E) removal of all of the H2 (g) 1

2 6) 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) 0.12 B) 0.50 C) 16 D) 0.25 E) ) At equilibrium,. A) the rates of the forward and reverse reactions are equal B) the rate constants of the forward and reverse reactions are equal C) all chemical reactions have ceased D) the value of the equilibrium constant is 1 E) the limiting reagent has been consumed 8) A substance that is capable of acting as both an acid and as a base is. A) autocratic B) conjugated C) miscible D) autosomal E) amphoteric 9) Ammonia is a. A) salt B) weak base C) strong acid D) strong base E) weak acid 10) The molar concentration of hydroxide ion in pure water at 25eC is. A) 0.00 B) 7.00 C) D) 1.00 E) ) Calculate the concentration (in M) of hydronium ions in a solution at 25eC with a poh of A) B) C) D) E) ) The equilibrium-constant expression depends on the of the reaction. A) temperature B) mechanism C) stoichiometry D) the quantities of reactants and products initially present E) stoichiometry and mechanism 13) 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) -K2 D) 1/2K E) 1/K2 2

3 14) The expression for Keq for the reaction below is. BaS (s) + 2O2 (g) BaSO4 (s) A) 1 PO 2 2 B) [BaSO 4] PO 2 C) [BaSO4] [BaS][O2]2 D) [O2]2 E) [BaS][O 2]2 [BaSO4] 15) 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) [NO 2] [N2O4] B) [NO2]2[N2O4] [NO2] C) [N2O4]2 D) [NO2][N2O4] E) [NO 2]2 [N2O4] 16) What is the ph of a M aqueous solution of barium hydroxide? A) 1.82 B) C) 1.52 D) E) ) Which one of the following will change the value of an equilibrium constant? A) varying the initial concentrations of products B) changing temperature C) adding other substances that do not react with any of the species involved in the equilibrium D) varying the initial concentrations of reactants E) changing the volume of the reaction vessel 18) Classify the following compounds as weak acids (W) or strong acids (S): nitrous acid hydrochloric acid hydrofluoric acid A) W S W B) W W W C) S W W D) W S S E) S S S 19) The conjugate acid of HSO4 - is A) H2SO4 B) HSO4 + C) SO4 2- D) HSO3 + E) H+ 20) Of the following acids, is not a strong acid. A) H2SO4 B) HNO3 C) HClO4 D) HNO2 E) HCl 3

4 21) Which one of the following is a BrMnsted-Lowry acid? A) CH3COOH B) HF C) HNO2 D) (CH3)3NH+ E) all of the above 22) The equilibrium constant for the gas phase reaction N2 (g) + 3H2 (g) 2NH3 (g) is Keq = at 300eC. At equilibrium,. A) reactants predominate B) only reactants are present C) roughly equal amounts of products and reactants are present D) only products are present E) products predominate 23) In which of the following reactions would increasing pressure at constant temperature not change the concentrations of reactants and products, based on Le Cha^telier's principle? A) 2N2 (g) + O2 (g) 2N2O (g) B) N2O4 (g) 2NO2 (g) C) N2 (g) + 3H2 (g) 2NH3 (g) D) N2 (g) + O2 (g) 2NO (g) E) N2 (g) + 2O2 (g) 2NO2 (g) 24) In basic solution,. A) [H3O+] < [OH-] B) [H3O+] = 0 M C) [H3O+] > [OH-] D) [OH-] > 7.00 E) [H3O+] = [OH-] 25) Of the following equilibria, only will shift to the left in response to a decrease in volume. A) N2 (g) + 3 H2 (g) 2 NH3 (g) B) 2HI (g) H2 (g) + I2 (g) C) 4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s) D) 2 SO3 (g) 2 SO2 (g) + O2 (g) E) H2 (g) + Cl2 (g) 2 HCl (g) 4

5 26) The effect of a catalyst on an equilibrium is to. A) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture B) increase the rate of the forward reaction only C) slow the reverse reaction only D) shift the equilibrium to the right E) increase the equilibrium constant so that products are favored 27) The magnitude of Kw indicates that. A) water autoionizes very slowly B) water autoionizes very quickly C) the autoionization of water is endothermic D) the autoionization of water is exothermic E) water autoionizes only to a very small extent 28) The conjugate base of HSO4 - is A) H2SO4 B) H3SO4 + C) SO4 2- D) HSO4 + E) OH- 29) In the reaction BF3 + F- BF4 - BF3 acts as a(n) acid. A) Lewis B) BrMnsted-Lowry C) Arrhenius and BrMnsted-Lowry D) Arrhenius, BrMnsted-Lowry, and Lewis E) Arrhenius 30) Of the following, which is the strongest acid? A) HIO3 B) HIO2 C) HIO4 D) HIO E) The acid strength of all of the above is nearly the same. 31) An aqueous solution contains 0.10 M NaOH. The solution is. A) highly colored B) basic C) acidic D) very dilute E) neutral 5

6 32) The Ka for HCN is What is the value of Kb for CN-? A) B) C) D) E) ) A BrMnsted-Lowry base is defined as a substance that. A) acts as a proton donor B) increases [H+] when placed in H2O C) decreases [H+] when placed in H2O D) acts as a proton acceptor E) increases [OH-] when placed in H2O 34) According to the Arrhenius concept, an acid is a substance that. A) causes an increase in the concentration of H+ in aqueous solutions B) tastes bitter C) reacts with the solvent to form the cation formed by autoionization of that solvent D) is capable of donating one or more H+ E) can accept a pair of electrons to form a coordinate covalent bond 35) Which one of the following statements regarding Kw is false? A) The value of Kw is always B) pkw is at 25eC C) Kw changes with temperature. D) Kw is known as the ion product of water. E) The value of Kw shows that water is a weak acid. 36) Which one of the following is the weakest acid? A) HNO2 (Ka = ) B) Acetic acid (Ka = ) C) HCN (Ka = ) D) HClO (Ka = ) E) HF (Ka = ) 6

7 Answer Key Testname: F.TST MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) D 2) C 3) D 4) A 5) A 6) E 7) A 8) E 9) B 10) E 11) A 12) C 13) E 14) A 15) E 16) B 17) B 18) A 19) A 20) D 21) E 22) E 23) D 24) A 25) D 26) A 27) E 28) C 29) A 30) C 31) B 32) A 33) D 34) A 35) A 36) C 1