(a) Calculate the enthalpy change (in J) when a 4.08 g sample of water at 26.4 °C and 1 atm is frozen to ice at -20.4°C and 1 atm.
(b) Calculate the enthalpy change (in J) when a 7.45 g sample of water at 48.5°C and 1 atm is converted to vapor at 139.3°C and 1 atm.