Question

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.

Answer 1

Depression of freezing point:  Freezing point depression is a basic property found in solutions that result from the transfer of solute molecules to a solvent.

The freezing points of solutions are always lower than that of the pure solvent and are directly proportional to the molality value of the solute.

As Fluorine is most electronegative has strongest electron withdrawing capacity.

As a consequent, trifluoroacetic acid is the strongest acid where acetic acid is the weakest one.

Therefore, trifluoroacetic acid ionizes most while acetic acid ionizes minimum.

More is the number of ions produced, more is the depression in freezing point.

Thus the depression of freezing point is maximum valued for trifluoroacetic acid and minimum for acetic acid.

Therefore depression of freezing point can be arranged  in the following order: Acetic Acid< trichloroacetic acid<trifloro acetic acid

Answer 2

Hey !!

The depression in freezing points are in the order:-

                CH₃COOH > Cl₃CCOOH > F₃CCOOH

Fluorine, being the most electronegative, has the highest inductive effect. As a result of this, trifluoroacetic acid is the strongest acid while acetic acid is the weakest acid. Hence, trifluoroacetic acid ionises to the largest extent while acetic acid ionises to the minimum extent to give ions in their solutions in water. Greater the ions produced is the depression in freezing point. Hence, the depression in freezing point is the maximum for the trifluoroacetic acid and minimum for acetic acid.

Hope it helps you !!