Which of the following is a similarity between the energy profiles of exothermic and endothermic reactions?

• A. Both absorb heat from the surroundings.
• B. Both show the products at a lower energy than the reactants.
• C. Both have an activation energy barrier that must be overcome for the reaction to proceed.
• D. Both have a negative enthalpy change (ΔH).

Answer: (C)

Verified step by step guidance

1. Understand that an energy profile diagram shows the energy changes during a chemical reaction, including the energy of reactants, products, and the activation energy barrier.
2. Recall that exothermic reactions release heat, so their products have lower energy than reactants, while endothermic reactions absorb heat, so their products have higher energy than reactants.
3. Recognize that both exothermic and endothermic reactions require an initial input of energy to reach the transition state, which is represented by the activation energy barrier.
4. Note that the activation energy barrier is the energy hump that must be overcome for the reaction to proceed, regardless of whether the reaction releases or absorbs heat.
5. Conclude that the similarity between the energy profiles of exothermic and endothermic reactions is that both have an activation energy barrier that must be overcome for the reaction to proceed.