An exergonic reaction releases energy to its surroundings, making it spontaneous with a negative Gibbs free energy change (ΔG<0). In contrast, an endergonic reaction absorbs energy from its surroundings, being non-spontaneous with a positive Gibbs free energy change (ΔG>0).
Endergonic vs. Exergonic Reaction
| Endergonic Reaction | Exergonic Reaction |
| An endergonic reaction is a chemical reaction that absorbs energy from its surroundings. | An exergonic reaction is a chemical reaction that releases energy either as heat or as work. |
| The Gibbs free energy change for an endergonic reaction is positive, indicating that the reaction is non-spontaneous. | The Gibbs free energy change for an exergonic reaction is negative, signifying that the reaction is spontaneous. |
| In endergonic reactions, energy is absorbed from the surroundings into the system. | In exergonic reactions, energy is released from the system to the surroundings. |
| An example of an endergonic reaction is photosynthesis in plants, where energy is stored in glucose. | An example of an exergonic reaction is cellular respiration in animals, where energy stored in glucose is released. |
| Endergonic reactions lead to an increase in the internal energy of the system. | Exergonic reactions result in a decrease in the internal energy of the system. |
| Endergonic reactions might still require an initial energy input to initiate, even though the overall process absorbs energy. | Although exergonic reactions release energy, an initial energy input might still be required to start the reaction. |
| Enzymes and catalysts can facilitate endergonic reactions by reducing the activation energy required. | Enzymes and catalysts can speed up exergonic reactions by reducing the necessary activation energy. |
| Endergonic reactions allow cells to perform work, build complex molecules, and maintain structural order. | Exergonic reactions provide energy that powers cellular processes and helps maintain cellular health. |
| Endergonic reactions are the opposite of exergonic reactions. | Exergonic reactions are the opposite of endergonic reactions. |
| Endergonic reactions are important in energy storage and in synthesis reactions in various industries. | Exergonic reactions are pivotal in energy production and in breakdown reactions across industries. |
What is Exergonic Reaction?
An exergonic reaction is a chemical reaction that releases energy in the form of work or heat. The Gibbs free energy change (ΔG) for an exergonic reaction is negative, indicating that the reaction is spontaneous.
Gibbs Free Energy (ΔG)
The Gibbs free energy change is a measure of the energy change in a system. For exergonic reactions:
ΔG<0
This indicates that the products of the reaction have lower free energy than the reactants.
Relationship to Endergonic Reactions
Opposite to exergonic reactions, endergonic reactions absorb energy from their surroundings. For endergonic reactions.
ΔG>0
Examples
Cellular respiration: Glucose is broken down in cells to produce water, carbon dioxide, and energy.
Combustion of wood: Wood burns in the presence of oxygen to produce carbon dioxide, water, and heat.
Importance in Biological Systems
- ATP Production: Adenosine triphosphate (ATP) is produced in an exergonic reaction during cellular respiration. The energy released is used to perform work in the cell.
- Driving Non-Spontaneous Reactions: Energy from exergonic reactions can be coupled to drive endergonic reactions, which are non-spontaneous and require an input of energy.
Thermodynamics
Exergonic reactions increase the entropy (disorder) of the system and its surroundings, making them thermodynamically favorable.
Activation Energy
While exergonic reactions are spontaneous in terms of energy, they may still require an initial energy input, called the activation energy, to get started. Enzymes and catalysts can lower this activation energy, making the reaction proceed faster.
Enzymes and Catalysts
In biological systems, enzymes play a crucial role in facilitating exergonic reactions. They do this by lowering the activation energy required for the reaction, thus speeding up the reaction rate.
Applications
- Industrial Processes: Many industrial chemical processes harness exergonic reactions to produce desired products and energy.
- Energy Production: Exergonic reactions are at the heart of energy production, including in fossil fuel combustion and in some renewable energy technologies.
What is Endergonic Reaction?
An endergonic reaction is a chemical reaction that requires an input of energy to proceed. In terms of Gibbs free energy change (ΔG), endergonic reactions have a positive value, indicating that they are not spontaneous.
Gibbs Free Energy
For endergonic reactions:
ΔG>0
This means that the products of the reaction have a higher free energy than the reactants.
Relationship to Exergonic Reactions
While exergonic reactions release energy, endergonic reactions take in energy. They’re kind of like the opposites of each other in terms of energy flow.
Examples
Photosynthesis: Plants take in sunlight, carbon dioxide, and water to produce glucose and oxygen.
Synthesis of ATP: In cells, Adenosine diphosphate (ADP) combines with inorganic phosphate (Pi) to produce ATP, absorbing energy in the process.
Importance in Biological Systems
Energy Storage: Endergonic reactions often store energy for later use. For example, the energy stored in ATP is used to power various cellular activities.
Building Molecules: Many of the body’s building processes, like making proteins from amino acids, are endergonic. They require energy to piece small molecules together into bigger ones.
Thermodynamics
Endergonic reactions decrease the entropy (or disorder) of the system, which means they make things more ordered or structured. This is why they need an energy input.
Activation Energy
Like exergonic reactions, endergonic ones also have an activation energy, or a little push to get started. Catalysts or enzymes can help reduce this initial energy barrier.
Enzymes and Catalysts
In our bodies, enzymes are the little helpers that make endergonic reactions happen faster. They make these energy-consuming processes more efficient.
Applications
Agriculture: Understanding endergonic processes like photosynthesis helps in improving crop yields.
Medical Science: Knowing how our cells use energy can lead to advances in medicine, especially in areas related to energy metabolism.
The terms “exergonic” and “endergonic” refer to energy changes in terms of work potential, while “exothermic” and “endothermic” relate to heat energy specifically. Here’s a breakdown of the differences:
Key Differences Between Exergonic and Endergonic Reactions
Overviewing Exergonic, Endergonic Reactions and Exothermic, Endothermic Reactions
Exergonic Reactions
- These reactions release free energy to their surroundings.
- They have a negative Gibbs free energy change (ΔG<0).
- They are generally spontaneous under constant temperature and pressure.
Endergonic Reactions
- These reactions absorb free energy from their surroundings.
- They have a positive Gibbs free energy change (ΔG>0).
- They are non-spontaneous under constant temperature and pressure.
Exothermic Reactions
- These reactions release heat energy to the environment.
- They have a negative enthalpy change (ΔH<0).
- The surroundings will typically feel warmer as a result.
Endothermic Reactions
- These reactions absorb heat energy from the environment.
- They have a positive enthalpy change (ΔH>0).
- The surroundings will typically feel cooler as a result.
Key Difference Between the Two
- “Exergonic” and “endergonic” are terms that focus on the change in Gibbs free energy and whether a reaction is spontaneous or not, considering both heat and work.
- “Exothermic” and “endothermic” specifically describe the heat flow of a reaction, without necessarily addressing spontaneity.
