Which of the following would have the strongest conjugate base?

  (a) H2O

 (b) H2S

 (c) NH3

 (d) PH3 (e) CH4
 

Which equation best describes an 0.10 M solution of a strong acid, such as hydroiodic acid (HI: K = 3 x 109)?

          (a) [H3O+]T ≈ CHI     (b) [H3O+]T ≈ [OH-]W     (c) [H3O+]T ≈ [HI]

         (d) [H3O+]T ≈ [H2O]    (e) [H3O+]T ≈ KaCa

 H2Gly is an acid and Na2Gly is a base. On the basis of the values of Ka1 and Ka2 for H2Gly and the values of Kb1 and Kb2 for Na2Gly, would an 0.10 M NaHGly solution be acidic, basic, or neutral? (H2Gly: Ka1 = 4.5 x 10-3, Ka2 = 2.5 x 10-10)

(a) slightly acidic 

(b) slightly basic

 (c) neutral (pH = 7)

  (d) there is no way to predict whether NaHGly is an acid or base.
 

 How would you increase the buffering capacity of a buffer made by adding NaHCO2 to an aqueous solution of HCO2H?

         (a) increase the concentration of HCO2H.

         (b) increase the concentration of NaHCO2.

          (c) increase the concentrations of both HCO2H and NaHCO2.

         (d) increase the ratio of the concentration of HCO2H to NaHCO2.

         (e) increase the ratio of the concentration of NaHCO2 to HCO2H.

Which of the following is the strongest Brønsted acid?

(a) NH4+ 

(b) HCl

 (c) HNO3

 (d) HSO4-

 (e) HClO4
 

 In a 0.10 M solution of H2Se, the Se2- concentration is:

  (a) [Se2-] = 0.10 x Ka2 = 1.0 x 10-11       (b) [Se2-] = Ka2 = 1.0 x 10-10

   (c) [Se2-] = (0.10 x Ka2)1/2 = 3.2 x 10-6   (d) [Se2-] = (0.10 x Ka1)1/2 = 4.1 x 10-3

     (e) none of the above

 When NH4Cl is added to an 0.10 M NH3 solution, the pH of this solution:

(a) increases 

(b) decreases

 (c) remains the same

  (d) increases at first and then decreases.

     (e) decreases at first and then increases.

 Calculate the pH of a buffer prepared by mixing 0.10 mol of sodium formate and 0.05 mol of formic acid in 1.0 L of solution. (HCO2H: Ka = 1.8 x 10-4)

 (a) 1.8 x 10-4

 (b) 3.44

(c) 4.05

 (d) 5.31

 (e) none of the above
 

The value of the equilibrium constant, Ka for the dissociation of formic acid in water,

HCO2H(aq) + H2O(l) ⇌ HCO2-(aq) + H3O+(aq)

would depend on:

 (a) the temperature 

(b) the pressure 

(c) the pH

 (d) the concentration of HOAc

  (e) the concentration of the OAc- ion.

NaHCO3 can be used to neutralize strong bases, such as NaOH. What conclusion can be drawn from the fact that the following acid-base reaction proceeds to the right as written?

                    HCO3-(aq) + OH-(aq) ➝ CO32-(aq) + H2O(l)

          (a) HCO3- is a stronger acid than H2O

         (b) HCO3- is a stronger base than CO32-

         (c) HCO3- is a stronger base than OH-

         (d) CO32- is a stronger base than OH-

         (e) H2O is a stronger acid than HCO3-

 Which of the following would make the best buffer?

 (a) a mixture of HCl and NaCl

(b) a mixture of NaOAc and NH3

(c) a mixture of HOAc and NH4Cl

(d) a mixture of NaOAc and NH4Cl

(e) a mixture of NH3 and NH4Cl