Answer
$\Delta H_{r} = ∑ \Delta H_{products} - ∑ \Delta H_{reactants}$.
Work Step by Step
Enthalpy of reaction = (sum of enthalpies of products) – (sum of enthalpies of reactants).
$\Delta H_{r} = ∑\Delta H_{products} - ∑\Delta H_{reactants}$.
Where,
$H_{r}$ = Enthalpy of reaction.
$ ∑H_{products}$ = sum of enthalpies of products.
$∑H_{reactants}$ = sum of enthalpies of reactants.
Whereas
Standard enthalpy of reaction = (sum of standard enthalpies of formation of products) – (sum of standard enthalpies of formation of reactants).
$\Delta H^{\circ}_{r} = ∑H^{\circ}_f{products} - ∑ H^{\circ}_f{reactants}$.
Where,
$\Delta H^{\circ}_{r}$ = Standard enthalpy of reaction.
$ ∑H^{\circ}_f{products}$ = sum of standard enthalpies of formation of products.
$∑H^{\circ}_f{reactants}$ = sum of standard enthalpies of formation of reactants.
