17. Acid and Base Equilibrium

Calculate the [H⁺] of a 0.50 M solution of methylammonium bromide, CH₃NH₃Br. The K_b of methylamine, CH₃NH₂, is given as 4.4 x 10^-4.

An unknown weak acid has an initial concentration of 0.55 M. What is the pH of the solution if the weak acid also has a pK_a of 5.79?

Calculate [H₃O⁺], [ClO₄^–], and [OH^–] in an aqueous solution that is 0.130 M in HClO₄(aq) at 25 °C.

What is the H⁺(aq) concentration in 0.05 M HCN(aq)? (the K_a for HCN is 5.0 x 10^-10.)

What is the pH of a 0.400 M solution of HF (K_a = 6.8 × 10^-4)?

What is the pH of a 0.0620 M solution of hydrocyanic acid, HCN (K_a = 4.9 × 10^-10)?