IV. Weak Acids and Weak Bases
IV-1. Introduction and Background IV-2. Sample Problems IV-3. Problem List IV-4. Weak Acid Problems IV-5. Weak Base Problems

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)     Ka = 1.8x10-5 at 25oC.
• 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)     Ka = 3.0x10-8 at 25oC.
• 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)     Ka = 1.3x10-1 at 25oC.

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: NH3(aq) + H2O NH4+(aq) + OH-(aq)     Kb = 1.8x10-5 at 25oC.
• IV-5(2). Calculate Kb 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: CH3NH2(aq) + H2O CH3NH3+(aq) + OH-(aq)

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