2CO + O_2 = 2CO_2
DeltaH"of reaction" = DeltaH_f^@ of "product(s)" - DeltaH_f^@ of "reactants"
The product in this reaction is CO
DeltaH_f^@ of CO is -253.7KJ/mol
The reactants in this reaction are O_2 and CO_2
But the DeltaH_f^@ of O_2 is not there
The DeltaH_f^@ of all elements is 0kJ/mol
So the DeltaH_f^@ of O_2 is
0kJ/mol
The combined DeltaH_f^@of products should be multiplied by their coefficients .
-253.7KJ/mol 2 + 0kJ/mol1 = -507.4kJ/mol
DeltaH_f^@ of products
CO_2 = -314.3kJ/mol
And remember also multiply by the coefficient
-314.3kJ/mol* 2 = -628.6
Plug the values in the equation
DeltaH"of reaction" = DeltaH_f^@ of "product(s)" - DeltaH_f^@ of "reactants"
"-628.6kJ/mol - (-507.4kJ/mol)"
DeltaH"of reaction"= "-121.2kJ/mol"
