Question

(a) The pH of black coffee is 5.0. Calculate the hydrogen ion concentration.

(b) The K_sp of barium sulphate is 1.5 × 10^-9 . Calculate the solubility of barium sulphate in pure water.

Calculate the solubility of barium sulphate in pure water.

Answer 1

(a) -log[H⁺] = 5 Or  log[H⁺] = -5

∴ [H⁺] = antilog(-5) = 10^-5

(b) BaSO₄(s) ⇌ Ba²⁺(aq) + SO₄^2-(aq)

K_sp = [Ba²⁺][SO₄^2-] = S² 

∴ S = \(\sqrt{K_{sp}}\) = \(\sqrt{1.5\times10^{-9}}\) = 3.873 x 10^-5