Given the following reaction :
`P : N_(2)(g)+2O_(2)(g)to2NO_(2)(g),DeltaH_(p)=16.18kcal`
`Q : N_(2)(g)+2O_(2)(g)toN_(2)O_(4)(g),DeltaH_(Q)=2.31kcal`
Based on the above facts :

The enthalpy of the reaction H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(g) is DeltaH_(1) and that of H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l) is DeltaH_(2) . Then

Calculate the enthalpy of vaporisation for water form the following: H_(2)(g) +1//2O_(2)(g) rarr H_(2)O(g),DeltaH =- 57.0 kcal H_(2)(g) +1//2O_(2)(g) rarr H_(2)O(l),DeltaH =- 68.3 kcal Also calculate the heat required to change 1g H_(2)O(l) to H_(2)O(g)