Print this list and try working these problems before checking your answers and looking at the hints.

Weak Acid Problems

• IV-4(1). What is the pH of the resulting solution when 0.500 moles of acetic acid are dissolved in water and diluted to 1.00 L?
  Unbalanced reaction: CH₃COOH_(aq) H⁺_(aq) + CH₃COO^-_(aq)     K_a = 1.8x10^-5 at 25^oC.

• IV-4(2). What is the pH of the resulting solution when 100.0 mL of 0.500 M of hypochlorous acid is mixed with 100.0 mL water?
  Unbalanced reaction: HOCl_(aq) H⁺_(aq) + OCl^-_(aq)     K_a = 3.0x10^-8 at 25^oC.

• IV-4(3). What is the pH of the resulting solution when 0.500 moles of trichloroacetic acid are dissolved in water and diluted to 1.00 L?
  Unbalanced reaction: CCl₃COOH_(aq) H⁺_(aq) + CCl₃COO^-_(aq)     K_a = 1.3x10^-1 at 25^oC.

Weak Base Problems

• IV-5(1). What is the pH of the resulting solution when 250.0 mL of a 0.300 M solution of ammonia added to 750.0 mL of water?
  Unbalanced reaction: NH_3(aq) + H₂O NH₄⁺_(aq) + OH^-_(aq)     K_b = 1.8x10^-5 at 25^oC.

• IV-5(2). Calculate K_b for methylamine if a solution prepared by dissolving 0.100 moles of methylamine in 1.00 L of water has a measured pH of 11.80.
  Unbalanced reaction: CH₃NH_2(aq) + H₂O CH₃NH₃⁺_(aq) + OH^-_(aq)