A 0.25 mol/L solution of benzoic acid, KC7H5O2 and antiseptic also used as a food preservative, has a pH of 2.40. Calculate the Ka of benzoic acid at SATP

Answer 1

Write the benzoic acid ionization.
Write the Ka expression.
Use pH = =log(H^+) to calculate (H^+).
Substitute into Ka expression and determine Ka.