How can I calculate the enthalpy change of a reaction?

Jul 11, 2018

How else but by measurement...or by enthalpy summation....?

Explanation:

For say a combustion reaction....

$C {H}_{4} \left(g\right) + 2 {O}_{2} \left(g\right) \rightarrow C {O}_{2} \left(g\right) + 2 {H}_{2} O \left(l\right)$

$\Delta {H}_{\text{rxn"^@=SigmaDeltaH_f^@""_"(products)"-SigmaDeltaH_f^@""_"(reactants)}}$

$\Delta {H}_{f}^{\circ}$ values are extensively tabulated...and these data are routinely available.

And so here we take the sum....

{−393.5+2xx(-286.0)-(-74.9)}*kJ·mol^-1-=-890.6*kJ*mol^-1" (i.e. per mole of reaction as written...)"

This site reports that the experimental value is $- 890.5 \cdot k J \cdot m o {l}^{-} 1$, and as we would expect the calculated value using tabulated data is completely kosher....