Question:
A sample of water under study was found to boil at $102^{\circ} \mathrm{C}$ at normal temperature and pressure. Is the water pure? Will this water freeze at $0^{\circ} \mathrm{C}$ ?
Solution:
Under normal temperature and pressure, the boiling point temperature of pure water is $100^{\circ} \mathrm{C}$. The boiling point of $102^{\circ} \mathrm{C}$ means that the given sample is impure and has non-volatile impurities present. This impure sample will have freezing point temperature below $0^{\circ} \mathrm{C}$. Please remember that the presence of impurities raises the boiling point tempeature of a liquid and lowers its freezing point.