posted by Taylor .
Calculate Delta H for 4NH3 + 5O2 --> 4NO + 6H2O
N2 +O2 --> 2NO DH= -180.5 kJ
N2 + 3H2 --> 2NH3 DH= -91.8 kJ
2H2 + O2 --> 2H2O DH= -483.6 kJ
Multiply equation 2 by 2 and reverse it.
Multiply equation 3 by 3 and leave as is.
Multiply equation 1 by 2 and leave as is.
Add the resulting equations.
Add the resulting delta Hs also, (after multipling AND changing the sign of those reversed.