Given these reactions, x ( s ) + 1 2 o 2 ( g ) ⟶ xo ( s ) δ h = − 665.9 k j / m o l xco 3 ( s ) ⟶ xo ( s ) + co 2 ( g ) δ h = + 190.1 k j / m o l what is δ h for this reaction? x ( s ) + 1 2 o 2 ( g ) + co 2 ( g ) ⟶ xco 3 ( s )

ΔH of reaction is -856 kJ/mol

Explanation:

The property ΔH is property which can be added to find the net change in enthalpy of reaction.

ΔH of first reaction is -665.9 kJ/mol

ΔH of second reaction is 190.1 kJ/mol

carefully looking at the third equation,

it is first reaction - second reaction.

thus, by Hess's law,

Hess's Law of Constant Heat Summation (or just Hess's Law) states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.

ΔH of third reaction is =

ΔH =  -856 kJ/mol