Practice Test 2B

Chapter 14 and Chapter 15 (Sections 1 – 6)

 

1.         Which of the following is a strong acid in water?

     

            A.        HF                               B.         HI                                            C.         H₃PO₄

            D.        H₂CO₃                          E.         HClO₂

 

   ANSWER:      B

 

2.         The net ionic equation for the neutralization of citric acid by a base is

      

                    H₃C₆H₅O₆(aq) + 3OH^-(aq)  à  3H₂O(l) + C₆H₅O₆^3-(aq)

      

            Therefore

     

            A.        citric acid is a strong acid.                    B.         the base is a strong base.

            C.         citric acid is the spectator ion.              D.        NH₃ could have been the base used.

            E.         none of these is true.

 

   ANSWER:      B

 

3.         H₂S(aq) + H₂O Û  H₃O⁺(aq) + HS^-(aq)

      

            HS^-(aq) + H₂O  Û   H₃O⁺(aq) + S^2-(aq)

      

            In the above reversible reactions, which are the Bronsted acids?

     

            A.        H₂S, H₂O, HS-                                                 B.         H₃O⁺, H₂O, S²- 

            C.         HS-, H₂O, S²-                                                 D.        H₂S, H₃O⁺, HS-

            E.         H₂O, H₃O⁺, HS-

 

   ANSWER:      D

 

4.         Consider the reactions represented by the following net ionic equations:

      

            1.  Mg(s) + 2H₃O⁺(aq)  à  Mg²⁺(aq) + H₂(g) + 2H₂O(l)

      

            2.  CO₃^2-(aq) + H₃O⁺(aq) à   HCO₃^-(aq) + H₂O(l)

      

            3.  H₃O⁺(aq) + OH^-(aq)  à  2H₂O(l)

      

            Which of the reactions are characterized as acid‑base?

     

            A.        3 only                          B.         1 and 2                                    C.         1 and 3

            D.        2 and 3                        E.         1, 2, and 3

 

   ANSWER:      D

 

 

5.         All of the following salts can be obtained from a strong acid and a strong base except

 

            A.        CsCl                             B.         LiI                                            C.         Ba(NO₃)₂

            D.        NaF                              E.         KClO₄

 

   ANSWER:      D

 

6.         What is the conjugate acid of HPO₄^2-?

     

            A.        H₃O⁺                            B.         HPO₄^2-                                     C.         H₂PO₄^- 

            D.        H₃PO₄                          E.         PO₄^3-  

 

   ANSWER:      C

 

7.         H₃PO₄ is a __________ acid, H₃PO₄ is a __________ acid than H₂PO₄^-, and H₂PO₄^-

            is a __________ acid than HPO₄^2-.

 

            A.        strong, stronger, stronger                      B.         weak, weaker, weaker

            C.         weak, stronger, stronger                       D.        strong, weaker, weaker

            E.         strong, weaker, stronger

 

   ANSWER:      C

 

8.         Which of the following statements is true in a reaction system at equilibrium?

 

A.        The number of collisions per unit time between reactants is equal to the number of collisions per unit between products.

            B.         Reactants are reacting to form products at the same rate as products are reacting to

form reactants.

C.         The product of the concentrations of the reactants is equal to the product of the concentrations of the products.

            D.        All concentrations of reactants and products are the same.

            E.         No products are being formed, and no reactants are being formed.

 

Answer            B

 

9.         The equilibrium constant, Kc , for the reaction      

 

 

                        H₂(g) + I₂(g)    Û   2HI(g)

      

            is 55 at 425 C. The value for the equilibrium constant will be changed if

 

            A.        concentrations are given in atmospheres instead of mol/L.

            B.         a catalyst is added to the reaction system.

            C.         the size of a reaction vessel is doubled.

            D.        the temperature is changed to 400 C.

            E.         additional HI is added to the reaction system.

 

Answer            D

10.       The equilibrium expression for K_c  for the system

      

                        CO₂(g) + CaO(s)  Û    CaCO₃(s)

      

            is

                           B.                                        C.         [CO₂]

            D.                               D.        [CO₂][CaO]

 

Answer                        D

 

11.       In which of the following does the reaction go farthest to completion (most products

            formed)?

     

            A.        K = 10⁵                        B.         K = 10^−5                       c.         K = 1000

            D.        K = 100                       E.         K = 1

 

Answer                        A

 

12.       Carbon disulfide and chlorine react according to the following equation:

      

                              CS₂(g)   +  3Cl₂(g)     Û   S₂Cl₂(g)   +  CCl₄(g)

      

When 1.00 mol of CS₂ and 3.00 mol of Cl₂ are placed in a 2.00‑L container and allowed to come to equilibrium, the mixture is found to contain 0.250 mol of CCl₄. What is the amount of Cl₂ at equilibrium?

 

A.      2.25 mol                        B.         2.75 mol                      C.         0.75 mol

D.        0.25 mol                      E.         0.50 mol

 

Answer                        A

 

13.       A mixture of NO and O₂ at a fixed temperature reacts according to the equation

      

         NO(g) + ½ O₂(g)    Û  NO₂(g)

      

When equilibrium is established, which of the following ratios is constant, regardless of the initial concentrations of NO and O₂?

 

            A.                           B.                            C.                         

 

            D.                     E.        

 

Answer                        C

14.       Which expression correctly describes the equilibrium constant for the following reaction?

      

         4NH₃(g)   +   5O₂(g)    Û    4NO(g)   +   6H₂O(g)

 

            A.        K_c = B.                

 

            C.                                     D.                   

 

            E.                    

 

Answer                        D

 

15.       If  K = 0.145 for:                     A₂   +   2B    Û    2AB,

 

then for:                                   AB    Û   B + ½ A₂, K would equal

 

A.  0.145.                                B.  ‑0.145.                               C.  0.381.

D.  2.63.                                  E.  6.90.

 

Answer                        D

 

16.       For which of the following equilibria would K_c  = K_p?

 

            A.        CaCO₃(s)  Û    CaO(s) + CO₂(g)                      B.         2H₂(g)  + O₂(g)  Û   2H₂O(g)

            C.         2NO₂(g)    Û    N₂O₄(g)                                   D.        2NO(g) + O₂(g)  Û   2NO₂(g)

            E.         O₃(g)  +  NO(g)    Û   NO₂(g)  +  O₂(g)

 

Answer            E

 

17.       For the reaction system:

      

            2HI(g)  Û   H₂(g)  +  I₂(g)

      

K_c  = 0.020 at 720 K. If the initial concentrations of HI, H₂, and I₂ are all 1.50 x 10^−3 M at 720 K, which one of the following statements is  correct ?

 

            A.        The system is at equilibrium.

                        B          The concentrations of HI and I  will increase as the system is approaching

equilibrium.

            C.         The concentrations of H  and HI will decrease as the system is approaching

equilibrium.

            D.        The concentration HI will increase as the system is approaching equilibrium.

            E.         The concentrations of H  and I  will increase as the system is approaching

equilibrium.

 Answer                       D

18.       A 1.00‑mol sample of HI is placed in a 1‑L vessel at 460^oC, and the reaction system is allowed to come to equilibrium. The HI partially decomposes, forming 0.11 mol H₂ and 0.11 mol I₂. What is the equilibrium constant for the reaction

      

        H₂(g)  +  I₂(g)  Û   2HI(g)

      

            at 460^oC?

 

            A.        0.020               B.         7.1                               C.         8.1

            D.        50                    E.         65

 

Answer                        D

 

19.       A mixture of nitrogen and hydrogen was allowed to come to equilibrium at a given temperature.

      

                                    3H₂  +  N₂    Û   2NH₃

      

            An analysis of the mixture at equilibrium contained 2.0 mol N₂, 3.0 mol H₂, and

1.5 mol NH₃ . How many moles of H₂ were present at the beginning of the reaction?

 

            A.        3.0                   B.         4.0                               C.         4.5

            D.        5.3                   E.         6.0

 

Answer                        D

 

20.       Consider the equilibrium:        N₂(g)  +  3H (g)  Û   2NH₃(g)

at a certain temperature. An equilibrium mixture in a 4.00‑L vessel contains

            1.60 mol NH₃, 0.800 mol N₂, and 1.20 mol H₂. What is the value of K_c?

 

            A.        9.00                 B.         29.6                             C.         3.37

            D.        17.1                 E.         7.41

 

Answewr         B

 

21.       The equilibrium constant for the reaction

      

        H₂(g)  +  I₂(g)  Û    2HI(g)

      

            is 62.5 at 800 K. What is the equilibrium concentration of I₂ if [HI] = 0.20 M and

[H₂] = 0.10 M at equilibrium?

 

            A.        3.2 x 10^−2 M                B.         8.0 x 10^−4 M                C.         0.20 M

            D.        0.10 M                         E.         6.4 x 10^−3 M

 

Answer            E

 

 

 

 

22.       Exactly 1.0 mol N₂O₄ is placed in an empty 1.0‑L container and is allowed to reach equilibrium described by the equation

      

        N₂O₄(g)  Û   2NO₂(g)

      

If at equilibrium the N₂O₄ is 20% dissociated, what is the value of the equilibrium constant  for the reaction under these conditions?

 

            A.        0.05                             B.         0.2                               C.         0.5

            D.        20                                E.         400

 

Answer                        B

 

23.       At a given temperature, 0.300 mol NO, 0.200 mol Cl₂, and 0.500 mol ClNO were placed in a  25.0‑L  container. The following equilibrium is established:

      

        2ClNO(g)    Û    2NO(g) + Cl₂(g)

 

At equilibrium, 0.600 mol ClNO are present. How many moles of Cl₂ are present at equilibrium?

 

            A.        0.050                           B.         0.100                           C.         0.150

            D.        0.200                           E.         0.250

 

Answer                        C

 

24.       At a given temperature, an equilibrium mixture of the reaction

      

        2NO(g)  +  O₂(g)   Û    2NO₂(g)

      

contains 0.090 mol NO, 0.120 mol O₂, and 0.060 mol NO₂ in a  3.00‑L  container. The value of  K_c  is

 

            A.        3.7.                              B.         6.1.                              C.         9.3.

            D.        11.                               E.         17.

 

Answer            D

 

25.       Consider the reaction

      

                        S₂Cl₂(l)  +  CCl₄(l)   Û   CS₂(g) + 3Cl₂(g)         DH^o  = 84.3 kJ

      

If the above reactants and products are contained in a closed vessel and the reaction system is at equilibrium, the number of moles of CS₂ can be increased by

 

            A.        adding some S₂Cl₂ to the system.

            B.         removing some CCl₄ from the system.

            C.         decreasing the size of the reaction vessel.

            D.        increasing the temperature of the reaction system.

            E.         adding some Cl  to the system.

 

Answer                        D

26.       Which of the following equilibria would not be affected by volume changes at constant temperature?

     

A.        H₂(g)  +  I₂(s)   Û   2HI(g)

            B.         C₂H₄(g)  +  H₂(g)   Û   C₂H₆(g)

            C.         4NH₃(g)  +  5O₂(g)   Û   4NO(g)  +  6H₂O(g)

            D.        SO₃(g)  +  NO(g)   Û   NO₂(g)  +  SO₂(g)

            E.         MgCO₃(s)   Û   MgO(s)  +  CO₂(g)

 

Answer                        D

 

27.       CS₂(g)  +  3Cl₂(g)   Û   CCl₄(g)  +  S₂Cl₂(g)

      

            At a given temperature the reaction above is at equilibrium when [CS₂] = 0.050 M,

[Cl₂] = 0.25 M, [CCl₄] = 0.15 M, and [S₂Cl₂] = 0.35 M. What would be the direction of the reaction when the reactants and products have the following concentrations: CS₂ = 0.15 M,

            Cl₂ = 0.20 M, CCl₄ = 0.30 M, and S₂Cl₂ = 0.28 M?

 

            A.        To the right

            B.         To the left

            C.         No change

            D.        Cannot predict unless we know the temperature

            E.         Cannot predict unless we know whether the reaction is endothermic or exothermic

 

Answer            B

 

28.       In which of the following reactions does a decrease in the volume of the reaction vessel at constant temperature favor formation of the products?

 

            A.        H₂(g)  +  I₂(g)   Û   2HI(g)

            B.         MgCO₃(s)   Û   MgO(s)  +  CO₂(g)

            C.         NO₂(g)  +  CO(g)   Û   NO(g) + CO₂(g)

            D.        2H₂(g)  +  O₂(g)   Û   2H₂O(g)

            E.         2O₃(g)   Û   3O₂(g)

 

Answer                        D

 

29.       At 5000 K, K = 1 for the reaction:       ½ N₂  +  ½ O₂  Û   NO.

            At 5000 K, one can be sure that, in all N₂, O₂ and NO systems,

 

            A.        [N₂]_  = [O₂] = 1.

            B .        [N₂] + [O₂] = 1.

            C.         [ ½ N₂] + [ ½ O₂ ] = [NO].

            D.        [N₂] = [O₂] = [NO].

            E.                    

 

Answer                        E

 

 

30.       For the reaction system:           2NO(g)  +  2CO(g) Û   N₂(g)  +  2CO₂(g) + heat,

 

            the conditions that favor maximum conversion of the reactants to products are

           

            A.        high temperature and high pressure.

            B.         high temperature, pressure being unimportant.

            C.         high temperature and low pressure.

            D.        low temperature and high pressure.

            E.         low temperature and low pressure.

 

Answer                        D

 

31.       For which of the following systems at equilibrium and at constant temperature will   decreasing the

            volume cause the equilibrium to shift to the right?

 

            A.        N₂(g)  +  3H₂(g) Û  2NH₃(g)                            B.         2H₂O(g) Û  2H₂(g)  +  O₂(g)

            C.         2NO₂(g) Û   2NO(g)  +  O₂(g)                         D.        NH₄Cl(s) Û   NH₃(g)  +  HCl(g)

            E.         H₂(g)  +  Cl₂(g) Û  2HCl(g)

 

Answer                        A

 

32.       For the following reaction system at equilibrium, which one of the changes would cause the             equilibrium to shift to the right?

      

                                2NOBr(g) Û  2NO(g)  +  Br₂(g)               DH  = 30 kJ

      

            A.        Decrease the volume of the reaction vessel.

            B.         Add some NO.

            C.         Remove some NOBr.

            D.        Add Br₂.

            E.         Increase the temperature.

 

Answer                        E

 

33.       Dinitrogen tetroxide readily undergoes decomposition to form red‑brown NO₂(g), as

            represented by the equation

      

                        N₂O₄(g) Û  2NO (g)

      

            At 25 C, 0.11 mol N₂O₄reacts to form 0.10 mol N₂O₄ and 0.02 mol NO₂. At 90 C, 0.11

            mol N₂O₄ forms 0.050 mol N₂O₄ and 0.12 mol NO₂. From these data, we can conclude that

 

            A.        N₂O₄ molecules react by a second‑order rate law.

            B.         N₂O₄ molecules react by a first‑order rate law.

            C.         the reaction is exothermic.

            D.        N₂O₄ molecules react faster at 25^oC than at 90^oC.

            E.         the equilibrium constant for the reaction increases with an increase in temperature.

 

Answer                        E

 

34.       For the reaction:           NO  +  ½ O₂   Û  NO₂,

            at 750 C the equilibrium constant K_p  is equal to 1.0. K_c  equals

 

            A.        1.0                               B.         K_p(RT)^3/2                      C.         K_p (RT)^-3/2   

            D.        K_p (RT)^2/3                     E.         K_p (RT)^1/2    

 

Answer                        E

 

35.       A solution has a hydroxide-ion concentration of 0.001 M (1 x 10^-3 M). What is the pH of the solution?

 

            A.        3                                  B.        14                                C.       11

            D.        7                                  E.         13

 

Answer            C

 

36.       Which of the following solutions has the  highest  hydroxide-ion concentration?

 

            A.        0.1 M HCl                                           B.        0.1 M H₂SO₄

            C.        a solution with pH = 5                                    D.        a solution with pOH = 12

            E.         pure water

 

Answer            E

 

37.       Which one of the following is  true  with respect to a 0.01 M formic acid solution,             HCOOH(aq)?

 

            A.        [H⁺(aq)] > [HCOO^-(aq)]                     B.        [H⁺(aq)] < [HCOO^-(aq)]

            C.        pH = 2.0                                              D.        pH > 2.0

            E.         [OH^-(aq)] > 10 

 

Answer            D

 

38.       Seawater has a pH of 8.10. What is its hydrogen-ion concentration?

 

            A.        1.0 x 10^-8 M                B.        8.0 x 10^-1 M                C.        7.9 x 10^-9 M

            D.        1.3 x 10^-6 M                E.         5.9 M

 

Answer            C

 

39.       The hydronium-ion concentration of a 0.0010 M acetic acid solution is 1.34 x 10^-4 M. What is the pH of the solution?

 

            A.        3.00                             B.        3.40                             C.        3.87

            D.        4.00                             E.         4.13

 

Answer            C

40.       A solution in which the pH is 8.7 would be described as

 

            A.        very acidic.                  B.        slightly acidic.             C.        neutral.

            D.        very basic.                   E.         slightly basic.

 

Answer            E

 

41.       A solution which is formed by combining 700. mL of 0.20 M HCl with 300. mL of

0.50 M NaOH has a [H₃O⁺] concentration of

 

            A.        0.20.                            B.        0.020.                          C.        0.010.

            D.        0.14.                            E.         1.0 x 10^-12

 

Answer            E

 

42.       The pH of a 0.10 M NH₄Cl solution is 5.13. The hydroxide-ion concentration of this         solution is

 

            A.        1.0 x 10^{-13                       Â}  B.        1.35 x 10^{-9                      Â}  C.        7.41 x 10^-6

            D.        1.3 x 10^{-5         Â}              E.         none of these.

 

Answer            B

 

43.       The hydronium-ion concentration of a 0.010 M acetic acid solution is 4.2 x 10^-4 M. The

pH of the solution is

 

            A.        2.0.                              B.        3.4.                              C.        4.0.

            D.        4.2.                              E.         4.7.

 

Answer            B

 

44.       For which of the following reactions is the equilibrium constant called an acid dissociation constant, K_a?

 

            A.        H₃O⁺(aq)  +  OH^- (aq)  Û  2H₂O

            B.        H⁺(aq)  +  OH^- (aq)  Û  H₂O

            C.        2NH₃(l)  Û  NH₄⁺(solv)  +  NH₂^-(solv)

            D.        NH₄⁺(aq)  +  H₂O  Û   NH₃(aq)  +  H₃O⁺(aq)

            E.         NH₃(aq)  +  H₂O  Û    NH₄⁺(aq)  +  OH^-(aq)

 

Answer            D

 

 

 

 

 

45.       Consider the K_a values for the following acids:

      

                        HF,      6.8 x 10^-4 

                        HNO₂,             4.5 x 10^-4 

                        HOBr,             2.5 x 10^-9

                        NH₄⁺, 5.6 x 10^-10 

                        HCN, 4.9 x 10^-10  

      

            Which of the following is the strongest base?

 

            A.        F^-                                B.        OBr^-                            C.        CN^-

            D.        NO₂^-                           E.         NH₃

 

Answer            C

 

46.       A 0.10 M solution of a weak monoprotic acid has a pH of 2.30. What is the equilibrium    constant, K_a, for this acid?

 

            A.        5.0 x 10^{-2         Â}              B.        5.0 x 10^{-3         Â}              C.        2.5 x 10^-4

            D.        2.5 x 10^{-5         Â}              E.         2.5 x 10^-6

 

Answer            C

 

47.      Hypobromous acid, HOBr, has an acid dissociation constant of 2.5 x 10^-6. What is the

pOH ^    in a 0.010 M HOBr solution.

 

            A.        5.30                             B.        7.70                             C.        8.30

            D.        8.70                             E.         9.30

 

Answer            D

 

48.       The relative strengths of the following acids increase in the order

      

                                                                 K_a

                        I.          H₃AsO₄            5.7 x 10^-3 

                        II.        HClO               2.8 x 10^-8 

                        III.       H₃PO₄              7.1 x 10^-3 

      

            A.        I < II < III                   B.        II < I < III                   C         III < II < I

            D         III < I < II                   E          II < III < I

 

Answer            B

 

 

 

49.       In a 0.10 M solution of sodium hydrogen sulfate, the HSO₄^- ion is 29% dissociated. For a            0.20 M solution of HSO₄^-, the percentage of dissociation would be

 

            A.        the same.

            B.        > 29%.

            C.        < 29%.

            D.        impossible to determine since K  has not been given.

            E.         none of these.

 

Answer            C

 

50.       What is the pH of a 0.050 M solution of pyridine, K_b = 1.4 x 10^-9?

 

            A.        5.1                               B.        4.4                               C.        9.6

            D.        8.9                               E.         10.2

 

Answer            D

 

51.       For which of the following reactions is the equilibrium constant called a basicity constant, K_b?

 

            A.        HCOOH(aq)  +  NH₃(aq)  Û   HCOO^−(aq)  +  NH₃(aq)

            B.        H₂O(aq)  +  OH^−(aq)   Û   2H₂O

            C.        HOCl(aq)  +  H₂O  Û   H₃O⁺(aq)  +  OCl^−(aq)

            D.        CH COOH(aq)  +  OH^−(aq)  Û  CH₃COO^−(aq)  +  H₂O

            E.         CH₃NH₂(aq)  +  H₂O  Û  CH₃NH₃⁺(aq)  +  OH^−(aq)

 

Answer            E

 

52.       The symbol K_b for H₂PO₄^- is the equilibrium constant for which reaction?

 

            A.        H₂PO₄^−  +  OH^−  Û   HPO₄^−   +   H₂O

            B.        H₂PO₄^−  +  H₂O  Û   HPO₄^−    +   H₃O⁺

            C.        H₂PO₄^−   +  H₂O  Û   H₃PO₄  +  OH^−

            D.        H₂PO₄^−   +  H₃O⁺   Û  H₃PO₄  +  H₂O

            E.         H₂PO₄^−   +  2H₂O  Û  2H₃O⁺  +   PO₄^3−  

 

Answer            C

 

53.       Consider the reaction:            NH₃  +  H₂O  Û  NH₄⁺   +  OH^-

            K_b for NH₃ is 2 x 10^-5. What is K_a for the NH₄⁺ ion?

 

            A.        2 x 10^−5                       B.        5 x 10^−7                                   C.        5 x 10^−10  

            D.        2 x 10^−19                      E.         1 x 10^−14  

 Answer           C

54.       A diprotic acid, H₂A, has values of K_a1 = 1.0 x 10^-6 and K_a2   = 1.0 x 10^-10. In a 0.10 M    solution of H₂A, what is [A^2-]?

 

            A.        0.10 M                         B.        0.20 M                         C.        3.2 x 10^−4 M

            D.        3.2 x 10^−6 M                E.         1.0 x 10^−10 M

 

Answer            E

 

55.       A 0.20 M solution of a diprotic acid, ascorbic acid, has an [H₃O⁺] of  4.0 x 10^−3 M. What is the value of K_a1?

 

            A.        4.0 x 10^−3                    B.        4.0 x 10^−4                                C.        8.0 x 10^−4 

            D.        8.0 x 10^−5                    E.         3.2 x 10^−7      

 

Answer            D

 

56.       Carbonic acid is a diprotic acid, H₂CO₃, with K_a1 = 4.2 x 10^−7 and K_a2 = 4.8 x 10^−11. The ion product for water is K_w  = 1.0 x 10^−14. What is the [HCO₃^−] concentration in a 0.037 M H₂CO₃ solution?

 

            A.        37 x 10^−2                     B.        1.2 x 10^−4                                C.        4.2 x 10^−7 

            D.        4.8 x 10^−11                   E.         1.6 x 10^−8 

 

Answer            B

 

57.       Carbonic acid is a diprotic acid, H₂CO₃, with K_a1 = 4.2 x 10^−7 and K_a2 = 4.8 x 10^−11. The ion product for water is K_w  = 1.0 x 10^−14. What is the equilibrium constant for the following carbonic acid reaction?

      

        H₂CO₃  +  2H₂O  Û    2H₃O⁺   +   CO₃^2−  

      

            A.        2.1 x 10^{−4                         Â}  B.        4.2 x 10^−7                                C.        2.4 x 10^−8 

            D.        4.8 x 10^−11                   E.         2.0 x 10^−17  

 

Answer            E

 

58.       Carbonic acid is a diprotic acid, H₂CO₃, with K_a1 = 4.2 x 10^−7 and K_a2 = 4.8 x 10^−11. The ion product for water is K_w  = 1.0 x 10^−14. What is the [OH^−] concentration of a solution that is 0.10 M in Na₂CO₃?

 

            A.        4.6 x 10^−3                    B.        2.0 x 10^−4                                C.        4.9 x 10^−5 

            D.        2.2 x 10^−6                    E.         1.4 x 10^−9 

      

Answer            A

 

 

59.       Oxalic acid is a relatively strong diprotic acid with K_a1   = 5.6 x 10^−2 and K_a2   =

5.1 x 10^−5. What is the [HC₂O₄^−] concentration in an oxalic acid solution that is 0.10 M?

 

            A.        0.10                             B.        5.1 x 10^{−5                         Â}              C.        0.050

            D.        0.027                           E.         0.073

 

Answer            C

 

60.       What is the percent dissociation of a 1.20 M CH₃COOH solution? (Ka  = 1.8 x 10^−5)

 

            A.        0.35                                         B.        0.39                             C.        0.42

            D.        0.46                                         E.         4.2

 

Answer            B

 

61.       Diethylamine, which we will represent by the symbol B, has a basicity constant

Kb  = 3.1 x 10^−4. The pH of a solution in which [B] = [BH⁺] is

 

A.        3.5.                                          B.        5.5.                              C.        7.0.

            D.        8.5.                                          E.         10.5.

 

Answer            E

 

62.       Which of the following salts when added to pure water will not change the pH of the       solution?

 

            A.        KI                                            B.        NaCH₃COO                            C.        BaS

            D.        LiHSO_{4                             Â}              E.         Na₂O

 

Answer            A

 

63.       Given that Ka  for HNO₂ is 5.0 x 10^−4, calculate the equilibrium constant for the reaction

      

                                    NO₂^−   + H₂O   ↔  HNO₂  + OH^−

      

            A.        5.0 x 10^−4                    B.        5.0 x 10¹⁰                                 C.        2.0 x 10^−4 

            D.        5.0 x 10¹⁸                     E.         2.0 x 10^−11  

 

Answer            E

 

64.       Which of the following, when added to water, will not change the pH?

           

            A.        NaHCO₃                     B.        NH₄Cl                                     C.        KCN

            D.        KCl                             E.         all of these

 

 

Answer            D