key term - Exergonic

Definition

Exergonic is a term used to describe a chemical reaction that releases energy, meaning the products of the reaction have less free energy than the reactants. These types of reactions are spontaneous and occur naturally without the need for an external energy input.

5 Must Know Facts For Your Next Test

1. Exergonic reactions release energy in the form of heat, which can be harnessed and used to drive other processes within a system.
2. The energy released in an exergonic reaction is often used to drive endergonic reactions, creating a coupled system where the spontaneous exergonic reaction provides the necessary energy for the non-spontaneous endergonic reaction.
3. Exergonic reactions are typically favored and occur naturally, as they result in a decrease in the overall free energy of the system, making them thermodynamically favorable.
4. The energy released in an exergonic reaction is represented as a negative value on an energy diagram, indicating that the products have less free energy than the reactants.
5. Exergonic reactions are often associated with a decrease in entropy, as the system becomes more ordered during the reaction.

Review Questions

• Explain how the energy released in an exergonic reaction can be used to drive other processes within a system.
  • In an exergonic reaction, the energy released in the form of heat can be coupled to an endergonic reaction, providing the necessary energy input to drive the non-spontaneous process. This coupling of exergonic and endergonic reactions allows for the efficient use of energy within a system, as the spontaneous release of energy from the exergonic reaction is harnessed to power other necessary reactions that would not occur naturally.
• Describe the relationship between the energy changes and the spontaneity of an exergonic reaction, as depicted in an energy diagram.
  • An energy diagram for an exergonic reaction shows that the products have less free energy than the reactants, resulting in a negative change in free energy (ΔG < 0). This negative value indicates that the reaction is spontaneous and will occur naturally without the need for an external energy input. The energy released during the reaction is represented as a downward slope on the energy diagram, demonstrating the thermodynamic favorability of the exergonic process.
• Analyze how the transition state and activation energy influence the rate and feasibility of an exergonic reaction.
  • The transition state represents the highest energy point along the reaction coordinate, which the reactants must overcome to form the products. In an exergonic reaction, the activation energy required to reach the transition state is typically lower than the energy released during the reaction, making the overall process favorable and spontaneous. However, the height of the activation energy barrier can still influence the rate at which the reaction occurs, as reactants must possess sufficient energy to overcome this barrier and reach the transition state. The relative energy levels of the reactants, transition state, and products, as depicted in the energy diagram, are crucial in determining the feasibility and kinetics of an exergonic reaction.

Related terms

Endergonic:

Endergonic refers to a chemical reaction that requires an input of energy to proceed, meaning the products have more free energy than the reactants.

Transition State:

The transition state is the highest energy point along the reaction coordinate, representing the unstable intermediate configuration that the reactants must pass through to form the products.

Energy Diagram:

An energy diagram is a graphical representation that shows the changes in free energy throughout the course of a chemical reaction, including the activation energy and the relative energy levels of the reactants and products.