Suppose that the reaction A¡products is exothermic and has an activation barrier of 75 kJ/mol. Sketch an energy diagram showing the energy of the reaction as a function of the progress of the reaction. Draw a second energy curve showing the effect of a catalyst.

Key Concepts

Exothermic Reactions

Exothermic reactions are chemical processes that release energy, usually in the form of heat, to the surroundings. This occurs when the total energy of the products is lower than that of the reactants, resulting in a negative change in enthalpy (ΔH). In the context of the given question, the reaction A → products releases energy, indicating that the products are more stable than the reactants.

Activation Energy

Activation energy is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that reactants must overcome to transform into products. In the question, the activation barrier of 75 kJ/mol indicates the energy needed to initiate the exothermic reaction, which is depicted as a peak in the energy diagram.

Catalysts

Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy. In the energy diagram, the effect of a catalyst is shown as a second curve that has a lower peak than the uncatalyzed reaction, illustrating that the catalyst reduces the energy barrier for the reaction to proceed.