pH of weak acids and bases

A solution containing a weak acid will likely have a pH

• approximately 7
• between 8 and 10
• below 7 but higher than 1
• around 1

Select the solution with the highest pH

• 0.1 M NaOH
• 0.1 M Ca(OH)₂
• 0.1 M HCl
• 0.1 M CH₃COOH

Which of these solutions, all with a concentration 0.2 M, will have the highest pH?

• HF  Ka = 7.2 x 10^-4
• benzoic acid Ka = 6.3 x 10^-5
• H₂SO₃ Ka = 1.2 x 10^-2
• H₃O⁺  Ka = 55.5

Which of these weak acids is the strongest?

• HF  Ka = 7.2 x 10^-4
• benzoic acid Ka = 6.3 x 10^-5
• H₂SO₃ Ka = 1.2 x 10^-2
• H₃O⁺  Ka = 55.5

Which of these bases is the weakest?

• F^-  Kb = 1.4 x 10^-11
• CN^- Kb = 2.5 x 10^-5
• OH^-  Kb = 55.5
• NH₃ Kb = 1.8 x 10^-5

A solution prepared with the base CN^- (Kb = 2.5 x 10^-5) has a concentration of 0.25 M of the base.  Calculate the pH for the solution.

• 4.6
• 9.4
• 2.6
• 11.4

A solution contains 0.04 M of a weak acid. Calculate the pH of the solutionknowing that the Ka for the acid is 1.6 x 10^-7

• It is not possible to solve if the identity of the acid is not known
• 4.1
• 4.9
• Because the Ka is very small, the pH is close to neutral (about 6)