Solutions

19.5 g of fluoro acetic acid (molar mass = 78 g mol⁻¹) is dissolved in 500 g of water at 298 K. The depression in the freezing point of water was 1^∘C. What is $K_a$ of fluoro acetic acid?

(For water, $K_f = 1.86$ K kg mol⁻¹). Assume molarity and molality to have same values.