February/March 2026 Paper 42

Define specific latent heat of fusion.

Explain why substances usually have a higher specific latent heat for vaporisation than for fusion.

An ice cube of mass $15.6\text{ g}$ at a temperature of $-18{}^{\circ }\mathrm{C}$ is removed from a freezer. The ice cube is immediately placed in an insulated beaker that contains a mass of $132.4\text{ g}$ of water at a temperature of $34{}^{\circ }\mathrm{C}$. The specific heat capacity of water is $4.19{\text{ kJ kg}}^{-1}{}^{\circ }{\mathrm{C}}^{-1}$. The specific heat capacity of ice is $2.11{\text{ kJ kg}}^{-1}{}^{\circ }{\mathrm{C}}^{-1}$. The specific latent heat of fusion of water is $336{\text{ kJ kg}}^{-1}$. The beaker has negligible specific heat capacity. The contents of the beaker are left to reach thermal equilibrium. Calculate the temperature, in ${}^{\circ }\mathrm{C}$, of the water in the beaker when thermal equilibrium is reached.