A swimmer coming out from a pool is covered with a film of water weighing about 18g. How much heat must be supplied to evaporate this water at 298 K? Calculate the internal energy of vaporisation at `100^@C`. `DeltaH_(vap)^@` for water at `373K = 40.66 kJ mol^(-1)`

Explanation

We can represent the process of evaporation as  
`H_(2)O_((l)) overset("vaporisation")(rarr)H_2O_((g)) , Delta = 1 - 0 = 1`
`Delta_(vap) E = Delta_(vap)H - pDeltaV =Delta_(vap) H - DeltanRT`
(assumig steam behaving as an ideal gas).
`Delta_(vap) E = 40.66 kJ mol^(-1) - (1)`
`(8.314 xx 10^(-3) KJ k^(-1) mol^(-1))(373 K) = 37.56 kJ mol^(-1)`.