Question

Which of the following expressions is correct to calculate enthalpy of a reaction?

• A. $\Delta H_{reaction} = \Sigma\,\Delta_{f}H_{reactants} - \Sigma\,\Delta_{f}H_{products}$
• B. $\Delta H_{reaction} = \Sigma \,B.E._{products} -\Sigma\,B.E._{reactants} $
• C. $\Delta H_{reaction} = \Sigma \,B.E._{reactants} -\Sigma \,B.E._{products} $
• D. $\Delta H_{reaction} = \Delta H_{1} \times \Delta H_{2} \times \Delta H_{3} \,\ldots$

Answer 1

Answer: (C)

Enthalpy change for a reaction expressions:
1. $\Delta H _{\text {reaction }}=\Sigma \cdot B \cdot E _{\text {reactant }}-\Sigma \cdot B \cdot E _{\text {product }}$
2. $\Delta H _{\text {reaction }}=\sum \Delta H _{\text {products }}-\sum \Delta H _{\text {reactants }}$
3. $\Delta H _{\text {reaction }}=\Delta H _{1}+\Delta H _{2}+\Delta H _{3}+\ldots$