The enthalpy change for chemical reaction is denoted aas `DeltaH^(Theta)` and `DeltaH^
Channel: Doubtnut
Date: 2020-07-26

The enthalpy change for chemical reaction is denoted aas `DeltaH^(Theta)` and `DeltaH^(Theta) = H_(P)^(Theta) - H_(R)^(Theta)`. The relation between enthalpy and internal enegry is expressed by equation:  `DeltaH = DeltaU +DeltanRT`  where `DeltaU =` change in internal enegry `Deltan =` change in number of moles, `R =` gas constant.   `H_(2)(g) +((1)/(2))O_(2)(g) = H_(2)O(l), DeltaH_(298K) = - 68.00kcal`  Heat of voporisation of water at `1` atm and `25^(@)C` is `10.00 kcal`. The standard heat of formation (in kcal) of `1` amol vapour a `25^(@)C` is