試題詳解

80. A weak acid HA is dissolved in enough water to prepare an acidic solution. The pH value and osmotic pressure of resulting solution at 27o C are 6 and 0.246 atm, respectively. What is the Ka of HA? (R = 0.082 L· atm/K·mol； assuming Van’t Hoff factor = 1)
(A) 1.00 × 10^–10
(B) 2.30 × 10^–10
(C) 1.10 × 10^–9
(D) 6.10 × 10^–9
(E) 5.80 × 10–8