1)The third equation must be halved.
H20–>H2+1/2O2
So ΔΗ3=483.6/2
2)The second equation must be halved and reversed.
CO2–>CO+1/2O2
So ΔΗ2=-(-566)/2=566/2
And now :
C+O2–>CO2
CO2–>CO+1/2O2
H2O—>H2+1/2O2
(You add them)
C+H2O—>CO+H2
ΔΗrxn=ΔΗ1+ΔΗ2’+ΔΗ3’=-393.5+283+241,8=131,3
