Question

If the reactants have a lower potential energy than the products, is the reaction exothermic or endothermic?

Short answer

The reaction is endothermic, since the products have a higher potential energy than the reactants.

Step-by-step solution

Understand the definitions of exothermic and endothermic reactions

An endothermic reaction absorbs heat from its surroundings. This means the products have a higher potential energy than the reactants. Conversely, an exothermic reaction releases heat to its surroundings, meaning the products have a lower potential energy than the reactants.

Apply definitions to the problem

Consider whether the reactants have a lower potential energy than the products. Decrease in potential energy implies that energy has been released to the surroundings, characterizing an exothermic reaction. On the other hand, if the potential energy increased during the reaction, then the reaction would have been endothermic.

Key concepts

Potential Energy

Potential energy refers to the stored energy in objects. It depends on their position or arrangement. In chemical reactions, potential energy is stored in chemical bonds. This energy can change as bonds break and form during reactions.

When reactants transform into products, potential energy changes occur. An increase in potential energy indicates that energy is absorbed from the surroundings. This is often seen in endothermic reactions. Conversely, a decrease in potential energy suggests that energy is released, typical in exothermic reactions. The comparison between the potential energy of reactants and products is crucial in determining whether a reaction is endothermic or exothermic.

Exothermic Reaction

An exothermic reaction is a type of chemical reaction that releases energy. This usually occurs in the form of heat. During these reactions, the energy required to break the bonds in reactants is less than the energy released upon formation of bonds in the products.

Characteristics of exothermic reactions include:

• Heat is released, often felt as warmth.
• Potential energy of products is lower than that of reactants.
• Temperature of the surroundings increases.

Examples of exothermic reactions include combustion and many oxidation reactions. The essence of an exothermic reaction lies in the fact that it transfers energy to its surroundings, causing the surroundings to warm up.

Heat Absorption

Heat absorption is a key feature of endothermic reactions. These reactions absorb heat from their environment, which is necessary for the reaction to proceed.

In an endothermic reaction:

• Heat is taken in from the surroundings.
• The temperature of the surroundings often decreases.
• Products have higher potential energy than reactants.

A classic example of heat absorption is when ice melts. As it absorbs heat from its surroundings, it transitions from a solid to a liquid. Understanding how heat absorption affects matter provides insight into many natural and industrial processes.