The bond enthalpy of the O-H bond in water H2O is the amount of energy required to break one mole of O-H bonds in the molecule. The bond enthalpy of the O-H bond in water is approximately 463 kJ/mol.To calculate the enthalpy change required to break one mole of O-H bonds in water, we need to consider that there are two O-H bonds in one molecule of water. Therefore, the enthalpy change for breaking one mole of O-H bonds in water can be calculated as follows:Enthalpy change = Bond enthalpy of O-H bond Number of O-H bonds in one molecule of waterEnthalpy change = 463 kJ/mol 2Enthalpy change = 926 kJ/molSo, the enthalpy change required to break one mole of O-H bonds in water is 926 kJ/mol.