Assuming that water vapour is an ideal gas, the internal energy change `(Delta U)` when `1 mol` of water is vapourised at `1` bar pressure and `100^(@)C`, (Given: Molar enthalpy of vapourization of water at `1` bar and `373K=41 kJ mol^(-1)` and `R=8.3J mol^(-1)K^(-1)`) will be:

Options

A. `4.100 kJ mol^(-1)`
B. `3.7904 kJ mol^(-1)`
C. `37.904 kJ mol^(-1)`
D. `41.00 kJ mol^(-1)`

Answer

C

Explanation

`H_(2)O(l)overset("vaporization")rarrH_(2)O(g)`
`Deltan_(g)=1-0=1`
`DeltaH=DeltaH+Deltan_(g)RT`
`=41-8.3xx10^(-3)xx373=37.9 kJ mol^(-1)`