To calculate the standard enthalpy change for the combustion of propane, we first need to write the balanced chemical equation for the combustion reaction:C3H8 g + 5O2 g 3CO2 g + 4H2O l Next, we need to find the standard enthalpies of formation Hf for each compound involved in the reaction. The values are as follows:Hf [C3H8 g ] = -103.85 kJ/molHf [O2 g ] = 0 kJ/mol since it's an element in its standard state Hf [CO2 g ] = -393.5 kJ/molHf [H2O l ] = -285.8 kJ/molNow, we can calculate the standard enthalpy change for the reaction H using the following equation:H = [sum of moles Hf of products ] - [sum of moles Hf of reactants ]H = [ 3 -393.5 + 4 -285.8 ] - [ 1 -103.85 + 5 0 ]H = -1180.5 + -1143.2 - -103.85 H = -2323.7 + 103.85H = -2219.85 kJSince this is the enthalpy change for 3 moles of propane, we need to divide by 3 to get the enthalpy change per mole of propane:H per mole of propane = -2219.85 kJ / 3H per mole of propane = -739.95 kJ/molSo, the standard enthalpy change for the combustion of 1 mole of propane gas C3H8 at standard conditions is approximately -739.95 kJ/mol.