If a reaction releases heat, what is the sign of ΔH, and how would this appear on an energy profile diagram?

• A. ΔH is positive; the products lie at a lower energy than the reactants.
• B. ΔH is negative; the products lie at a lower energy than the reactants.
• C. ΔH is negative; the reactants lie at a lower energy than the products.
• D. ΔH is zero; energy is unchanged.

Answer: (B)