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

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 !!

Answer 2

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[hint] :
Depression in freezing point to a solvent due to The dissolution of a solute in dependent on the degree of dissociation.

The depression in freezing point of a solute in water depends upon the number of particles are ions in its aqueous solution or its degree of dissociation $( \alpha )$]
These acids are arranged in the order of their increasing acidic strength

CH3COOH < CCL3COOH < CF3COOH

Fluorine is more electronegative than chlorine so trifluoroacetic acid is stronger than trichloroacetic acid which in turn stronger than Acetic Acid the order of depression in freezing point is also the same .