Answer:
2.76.
Explanation:
C of acid = [(MV)CH₃COOH - (MV)NaOH] / Vtotal.
C of acid = [(0.35 M)(52.0 mL) - (0.4 M)(17.0 mL)] / (69.0 mL) = 0.165 M.
∵ [H⁺] = √(Ka.C)
∴ [H⁺] = √(1.8 x 10⁻⁵)(0.165 M) = 1.72 x 10⁻³.
∵ pH = - log[H⁺] = - log (1.72 x 10⁻³) = 2.76.