The enthalpy of vapourisation of liquid water using the data :
`H_(2)(g)+1//2O_(2)(g)rarr H_(2)O(l) , Delta =-285.77 KJ mol^(-1)`
`H_(2)(g)+1//2O_(2)(g)rarr H_(2)O(g) , Delta H=-241.84 KJ mol^(-1)`

The enthalpy of vaporisation of liquid water using the data H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l) , DeltaH=-285.77 kJ//mol H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(g) , DeltaH=-241.84 kJ//mol

The enthalpy of vaporisation of liquid water using the data H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l) , DeltaH=-285.77 kJ//mol H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(g) , DeltaH=-241.84 kJ//mol

The enthalpy of vapourisation of liquid water using the data: (i) H_2(g) + (1/2) O_2(g) to H_2O(l), DeltaH = -285.77 kJ/mol, (ii) H_2(g) + (1/2) O_2(g) to H_2O(l), DeltaH = -241.84 kJ/mol,

Calculate the standard enthalpy of formation of acetylene from the following data : C_((g))+O_(2(g))rarr CO_(2(g)),DeltaH^(@)=-393kJ mol^(-1) H_(2(g))+(1)/(2)O_(2(g)) rarr H_(2)O_((l)),DeltaH^(@)=-285.8kJ mol^(-1) 2C_(2)H_(2(g))+5O_(2(g))rarr 4CO_(2(g))+2H_(2)O_((l)),DeltaH^(@)=-2598.8kJ mol^(-1) .

Diborane is a potentail rocket fuel which undergoes combusion according to the reaction B_(2)H_(6)(g)+3O_(2)(g)rarrB_(2)O_(3)(s)+3H_(2)O(g) From the following data, calculate the enthalpy change for the combustion of diborane 2B(s)+(3//2)O_(2)(g)rarrB_(2)O_(3)(s) DeltaH= -1273 kJ mol^(-1) H_(2)(g)+(1//2)O_(2)(g)rarrH_(2)O(1) " "Delta H= -286 kJ mol^(-1) H_(2)O(1)rarrH_(2)O(g)" "DeltaH=44 kJ mol^(-1) 2B(s)+3H_(2)(g)rarrB_(2)H_(6)(g)" "Delta H= 36kJ mol^(-1)