18. Aqueous Equilibrium

The K_b of C₆H₅NH₂ (aniline) is 3.9 × 10⁻¹⁰. Determine pH of a buffer solution made up of 500 mL of 1.4 M C₆H₅NH₂ and 230 mL of 2.3 M C₆H₅NH₃⁺.

Determine the buffer component concentration ratio (CB/WA) for a buffer with a pH of 4.7. K_a of boric acid (H₃BO₃) is 5.4 × 10⁻¹⁰.

Calculate mass of NaN₃ that needs be added to 1.8 L of 0.35 M HN₃ in order to make a buffer with a pH of 6.5. K_a of hydrazoic acid is 1.9 × 10⁻⁵.

Which of the following weak acid-conjugate base combinations would result in an ideal buffer solution with a pH of 9.4?

a) formic acid (HCHO₂) and sodium formate (K_a = 1.8 x 10^-4)

b) benzoic acid (HC₇H₅O₂) and potassium benzoate (K_a = 6.5 x 10^-5)

c) hydrocyanic acid (HCN) and lithium cyanide (K_a = 4.9 x 10^-10)

d) iodic acid (HIO₃) and sodium iodate (K_a = 1.7 x 10^-1)

buffer 2: 50.0 mL of 0.18 M NH₃ with 5.0 mL of 0.36 M HBr.

What is the pH of a solution of 0.300 M HNO₂ containing 0.100 M NaNO₂? (K_a of HNO₂ is 4.5 × 10^–4)

What is the ratio of [A^–]/[HA] at pH 5.75? The pK_a of formic acid (methanoic acid, H–COOH) is 3.75.

What ratio of NaCN to HCN is needed to prepare a pH 10.00 buffer? (K_a of HCN is 4.9 × 10^-10)

How much more acetic acid (pK_a = 4.76) than acetate should be in solution to maintain a pH of 4.00?

Calculate the pH when 40.0 mL of 0.150 M KOH is mixed with 20.0 mL of 0.300 m HBrO (K_a = 2.5 × 10^-9)