Solution for the second major exam
Calculate pH of the following solutions:
(a) 1.00x10-3 M potassium hydroxide, KOH, solutions
(b) 0.25 M propanoic acid, CH3.CH2.CH2.COOH. Ka for propanoic acid is 1.3x10-5
(c) 10.0 mL of 0.1 M HCl and 50.0 mL of 0.01 M NaOH
Question # 2 (24 points)
2. (a) What is the concentration of acetic acid, CH3COOH, if it is 3.0% ionized.
Ka for acetic acid = 1.75x10-5.
(b) Calculate the pH of 0.05 M solution of sodium benzoate, C6H5COOH.
Ka for benzoic acid = 6.30 x10-5.
(c) Calculate the pH of a solution prepared by mixing of 5.0 mL of 0.2 M NH3 with 100
mL of 0.01 M HCl. Kb for NH3 is 1.75x10-5
Question # 3 (24 points)
(a) an acetic acid-sodium acetate buffer of pH 5.00 is 0.100 M in NaOAC. Calculate the pH
after the addition of 10.0 mL of 0.10 M NaOH to 100 mL of the buffer. The reaction is,
NaOH + CH3COOH  CH3COONa + H2O
(b) How many grams of solid ammonium chloride, NH4Cl (molar mass is 53.5) must be
added to 500 mL of 0.0200 M NH3 to prepare 1.000-liter buffer solution of pH 9.30
after dilution with distilled water?
# 3a
3b