Acids and Bases AP Test Practice Problems
a) What is the pH of a 2.0 molar solution of acetic acid? Ka = 1.8 10
b) A buffer solution is prepared by adding 0.10 liter of 2.0 molar acetic acid solution to 0.1 liter of a
1.0 molar sodium hydroxide solution. Compute the hydrogen ion concentration of the buffer
c) Suppose that 0.10 liter of 0.50 molar hydrochloric acid is added to 0.040 liter of the buffer
prepared in (b). Compute the hydrogen ion concentration of the resulting solution.
Sodium benzoate, C6H5COONa, is the salt of the weak acid, benzoic acid, C6H5COOH. A 0.10 molar
solution of sodium benzoate has a pH of 8.60 at room temperature.
a) Calculate the [OH–] in the sodium benzoate solution described above.
b) Calculate the value for the equilibrium constant for the reaction:
– + H2O ⇌ C6H5COOH + OH
c) Calculate the value of Ka, the acid dissociation constant for benzoic acid.
d) A saturated solution of benzoic acid is prepared by adding excess solid benzoic acid to pure
water at room temperature. Since this saturated solution has a pH of 2.88, calculate the molar
solubility of benzoic acid at room temperature.
An approximately 0.1–molar solution of NaOH is to be standardized by titration. Assume that the
following materials are available.
• Clean, dry 50 mL buret
• 250 mL Erlenmeyer flask
• Wash bottle filled with distilled water
• Analytical balance
• Phenolphthalein indicator solution
• Potassium hydrogen phthalate, KHP, a pure solid monoprotic acid (to be used as the primary standard)
a) Briefly describe the steps you would take, using the materials listed above, to standardize the
b) Describe (i.e., set up) the calculations necessary to determine the concentration of the NaOH
c) After the NaOH solution has been standardized, it is used to titrate a weak monoprotic acid, HX.
The equivalence point is reached when 25.0 mL of NaOH solution has been added. In the space
provided at the right, sketch t