10. Acids and Bases

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)