Question

Which statement describes the potential energy diagram of an endothermic reaction?

Answer 1

Answer: option C. The potential energy of the products is greater than the potential energy of the reactants.

Explanation:

1) The potential energy diagram shows the evolution of the potential chemical energy of a process or reaction, measured as energy of the chemical bonds, including the reactants, the intermediates, the activated complex, and the products.

The vertical axis is the potential energy (energy of the chemical bonds) of the substances, and the horizontal axis is time.

2) An endothermic reaction is that that absorbs energy from the surroundings to lead the substances to a higher chemical potential energy. The surroundings will get cooler and the products will content more potential energy than the reactants.

3) At the beginning, the potential energy is that of the reactants; as the reaction progress, the potential energy increase, since the particles (molecules, atoms or ions) have to reach the peak, which is the point where the activated complex has been formed. From that point, the potential energy starts to decrease until the final products are formed.

3) The energy of the final state (the products) will be higher than the energy of the initial state, if the reaction absorbed heat from the surroundings (which is what an endothermic reaction is). If the final energy is less than the initial one, the products have released energy and that is an exothermic reaction.

4) The curve (diagram) shows that, and the choice C indicates correctly the change in the energy for an endothermic reaction: The potential energy of the products is greater than the potential energy of the reactants.