Using the equations N2(g)+3H2(g)2NH3 (g) H=91.8kJ/mol C(s)+2H2(g)CH4 (g) H=74.9kJ/mol H2(g)+2C(s)+N2(g)2HCN(g)H=270.3kJ/mol Determine the enthalpy (in kJ/mol ) for the reaction CH4(g)+NH3(g)HCN(g)+3H2(g)