Question

Imagine a huge ice cube of 1 km length. We want to freeze a water drop with this huge block. You will be surprised to know that this huge block of ice is incapable of even freezing a drop of water kept in it. Explain why the huge ice block is unable to freeze the water drop.

Answer 1

Consider a water drop at the centre of a huge ice cube. Initially, ice starts absorbing heat from the water drop and the temperature of water starts decreasing and becomes $0{}^{o}C$- same as that of ice.So, thermal equilibrium is reached. During thermal equilibrium, ice cannot absorb heat from water, as both have same temperature. If the water $0{}^{o}C$ has to be frozen to ice, the 80 cal of heat should be removed from every gram of water. This is not possible due to thermal equilibrium and hence the water drop cannot be frozen.