To calculate the standard enthalpy of formation of ethane C2H6 , we need to consider the bond energies of the reactants and products.The equation for the formation of ethane is:C graphite + 3H2 g -> C2H6 g First, let's determine the bond energies of the reactants:1 C-C bond in graphite: 0 kJ/mol since it's in its standard state 3 H-H bonds in H2 g : 3 * 436 kJ/mol average bond energy for H-H Total bond energy of reactants = 0 + 3 * 436 = 1308 kJ/molNow, let's determine the bond energies of the products:1 C-C bond in C2H6: 347 kJ/mol6 C-H bonds in C2H6: 6 * 413 kJ/molTotal bond energy of products = 347 + 6 * 413 = 347 + 2478 = 2825 kJ/molFinally, we can calculate the standard enthalpy of formation of ethane C2H6 using the bond energies of the reactants and products:Hf = Bond energy of products - Bond energy of reactantsHf = 2825 kJ/mol - 1308 kJ/molHf = 1517 kJ/molThe standard enthalpy of formation of ethane C2H6 is 1517 kJ/mol.