Standard enthalpy of vaporisation`DeltaV_(vap).H^(Theta)` for water at `100^(@)C`is`40.66kJmol^(-1)`.The internal energy of Vaporization of water at` 100^(@)C("in kJ mol"^(-1))`is

Options

A. `+37.56`
B. `-43.76`
C. `+ 43.76`
D. `+40.66`

Answer

A

Explanation

`underset(1 "mole")(H_(2)O(l)) rarrunderset("1 mole")(H_(2)O(g)), Deltan_(g)=1`
`DeltaU =DeltaH - Deltan_(g)RT`
`= 40.66 xx 1000 J mol^(-1)-1 xx 8.314 JK^(-1) xx 373 K`
`= 40660 - 3101 J mol^(-1)`
`=37559 J mol^(-1)`
`=37. 56 kJ mol^(-1)`