David Sang and Graham Jones Solutions for Chapter: Thermal Physics, Exercise 9: Questions

The specific latent heat of fusion of water is $330 \mathrm{kJ} \mathrm{kg}-1$. Calculate the energy needed to change $2.0 \mathrm{g}$ of ice into water at $0°\mathrm{C}$. Suggest why the answer is much smaller than $6000 J$.

A sample of alcohol is heated with a $40 \mathrm{W}$ heater until it boils. As it boils, the mass of the liquid decreases at a rate of $2.25 \mathrm{g}$ per minute. Assuming that 80% of the energy supplied by the heater is transferred to the alcohol, estimate the specific latent heat of vaporisation of the alcohol. Give your answer in $\mathrm{kJ} {\mathrm{kg}}^{-1}$.