Question

What is the heat of formation of water (H2O) at standard conditions (25°C and 1 atm pressure) if the enthalpy change of the reaction 2H2(g) + O2(g) → 2H2O(l) is -484 kJ/mol?

Answer 1

The heat of formation of water  H2O  can be calculated using the given enthalpy change of the reaction:2H2 g  + O2 g   2H2O l ; H = -484 kJ/molSince the reaction produces 2 moles of H2O, we need to divide the enthalpy change by 2 to find the heat of formation for 1 mole of H2O:Heat of formation of H2O =  -484 kJ/mol  / 2 = -242 kJ/molSo, the heat of formation of water  H2O  at standard conditions  25C and 1 atm pressure  is -242 kJ/mol.