Question

Explain how lumps of ice are at 273° k more effective in cooling drinking water than water at 273°k.

Answer 1

Ice at 273 K is more effective in cooling than water at the same temperature.

This is due to latent heat of fusion, meaning hidden heat.This signifies that the energy possessed by water is more than that of ice because while heating ice, the heat energy is used up in breaking the bonds b/w the particles without affecting the temp. Thus, ice has less energy than water and hence it is more effective in cooling as compared with water.
(Note : Its 273 K not 273° k :) )

Answer 2

Ice at 273 K will absorb heat energy or latent heat from the medium to overcome the fusion to become water. Hence the cooling effect of ice is more than the water at same temperature because water does not absorb this extra heat from the medium.