The combustion of methane CH4 can be represented by the following balanced chemical equation:CH4 g + 2O2 g CO2 g + 2H2O l The standard enthalpy change of combustion for one mole of methane Hc is -890.3 kJ/mol.To find the enthalpy change for the combustion of 2 moles of methane, simply multiply the standard enthalpy change of combustion for one mole by the number of moles:H = Hc number of moles H = -890.3 kJ/mol 2 mol H = -1780.6 kJSo, the enthalpy change for the combustion of 2 moles of methane at standard conditions is -1780.6 kJ.