Which of the following expressions best represents the enthalpy change,

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

\Delta H_{\mathrm{rxn}}

, of a chemical reaction when average bond energies are used? (a)

\Delta H_{\mathrm{rxn}}=\sum E(\text{bonds formed})-\sum E(\text{bonds broken})

(b)

\Delta H_{\mathrm{rxn}}=\dfrac{\sum E(\text{bonds broken})}{\sum E(\text{bonds formed})}

(c)

\Delta H_{\mathrm{rxn}}=\sum E(\text{bonds broken})-\sum E(\text{bonds formed})

(d)

\Delta H_{\mathrm{rxn}}=\sum E(\text{bonds broken})+\sum E(\text{bonds formed})