The depression in freezing point of water observed for the same amount of acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order given above. Explain briefly.

The depression in freezing point of water observed for the same amount of

acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order

given above. Explain briefly.

Solution

Carboxylic acid will undergoes in a partial dissociation because it has CH₃ there  which is non polar  while water is a polar and polar dissolve in polar and non polar in non polar. Fluorine is most electronegative substance so that it has the highest electron withdrawing inductive effect. Colligative properties of solution depends upon nature of the solute. Tri­fluoroacetic acid ionizes to the largest extent. Value of colligative properties is directly proportional to ability of dissociation of the solute.Hence the order of the depression in freezing point of water increases in the order

CH₃COOH < C1₃CCOOH < F₃CCOOH.