A 0.15 m aqueous solution of a weak acid has a freezing point of - 0.31 °C. What is the percent ionization of this weak acid at this concentration? The molal freezing- point- depression constant of water is 1.86 °C/m.
A) 35
B) 31
C) 89
D) 17
E) 11

Question

Quizplus · Accepted Answer

The freezing point depression is calculated using ΔTf = i * Kf * m. Here, ΔTf = 0.31°C, Kf = 1.86°C/m, and m = 0.15 m. Solving for i gives i = ΔTf / (Kf * m) = 0.31 / (1.86 * 0.15) ≈ 1.11. Since i = 1 + α (where α is the degree of ionization), α = i - 1 = 0.11 or 11%.

A 015 M Aqueous Solution of a Weak Acid Has a a Freezing