In the energy profile for a three-step reaction

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

Problem

In the energy profile for a three-step reaction, the enthalpy of the reactants is defined as

0\,\text{kJ}

. The stable intermediate lies at

-15\,\text{kJ}

, and the products lie at

+25\,\text{kJ}

. Which statement best describes the overall enthalpy change,

\Delta H

, for the reaction? (a)

\Delta H = -25\,\text{kJ}

; the reaction is exothermic (b)

\Delta H = -15\,\text{kJ}

; the reaction is exothermic (c)

\Delta H = +25\,\text{kJ}

; the reaction is endothermic (d)

\Delta H = +40\,\text{kJ}

; the reaction is endothermic