ΔH rxn = 434.7 kJ
Further explanation
Given
C+O₂⇒CO₂ ΔH=-393.5 (reaction 1)
2CO+O₂⇒2CO₂ ΔH=-566 (reaction 2)
2H₂O⇒2H₂+O₂ ΔH=483.6 (reaction 3)
Required
ΔH rxn
Solution
Reaction 1 : no change
C+O₂⇒CO₂ ΔH=-393.5
Reaction 2 : the reaction is reversed and divided by 2
CO₂⇒ CO+1/2O₂ ΔH=-283
Reaction 3 : divided by 2
H₂O⇒H₂+1/2O₂ ΔH=241.8
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C+H₂O⇒CO + H₂ ΔH rxn= -434.7 kJ