Question

Calculate the pH of a solution that is prepared by dissolving 0.183 mol of pentafluorobenzoic acid (C₆F₅COOH, K_a = 3.30×10^-2) and 0.400 mol of hydrocyanic acid (HCN, K_a = 6.17×10^-10) in water and diluting to 2.30 L. Also, calculate the equilibrium concentrations of C₆F₅COOH, C₆F₅COO^-, HCN, and CN^-. Do not make an approximation unless the initial acid concentration is greater than 1000 × K_a. (Hint: The pH will be determined by the stronger acid of this pair.)

pH = ?

[C₆F₅COOH] = ? M

[C₆F₅COO^-] = ? M

[HCN] = ? M

[CN^-] = ? M