Question

What two liquids when mixed occupy less combined volume than the sum of their individual volumes (at room temp, sea-level pressure)? I've heard that mixing 1 unit volume of water with one unit volume of antifreeze occupies less than 2 units of combined volume. Is this true? What is the shrinkage?

Answer 1

This is the case of negative deviation from Raoult's Law.

Let say we have two liquids i.e. A and B. The forces of attraction in liquid A is A-A type and in B is B-B type. When mixed they have forces of attraction of A-B type. If forces A-A type and B-B type is less stronger than A-B type change in volume of mixing will be negative i.e. volume of solution will be lesser than the sum of volume of liquids A and B.

e.g. chloroform and acetone show extensive hydrogen bonding.