Exergonic vs Endergonic: Detailed Explanations And Insights

Exergonic and endergonic reactions are two types of chemical reactions that dictate the flow of energy in a system. The key difference is in the free energy change that occurs during the reaction. An exergonic reaction releases free energy, while an endergonic reaction absorbs it.

It’s worth noting that both exergonic and endergonic reactions can be reversible meaning they can go in either the forward or reverse direction depending on environmental conditions such as temperature and reactant concentrations. The direction of the reaction is determined by comparing the free energies of the products and reactants under standard conditions.

In conclusion, exergonic reactions release free energy and are spontaneous, while endergonic reactions need an energy input and are non-spontaneous. It’s essential to understand these different types of reactions for many biological processes and industrial applications.

To figure out whether a reaction is favorable (exergonic) or unfavorable (endergonic), look at the change in Gibbs free energy (∆G). Exergonic reactions: Like a cat playing with a mouse, these reactions release energy and are the life of the metabolic party.

Exergonic reactions

To understand exergonic reactions, let’s dive into the world of energy transformations. In exergonic reactions, the focus is on the release of free energy. In the first subsection, we’ll explore the definition and examples of exergonic reactions, shedding light on their characteristic traits. Then, we’ll delve into the fascinating concept of how these reactions result in the release of free energy. Get ready to unravel the dynamics of exergonic reactions and their energetic outcomes.

Definition and examples of exergonic reactions

Exergonic reactions are known as energy-releasing reactions. Bonds are broken and energy is released, in a process that happens spontaneously. It’s vital for many biological processes.

A classic example include

  • Glucose breakdown in cellular respiration. When glucose molecules are broken down, energy is released and used to make ATP. It’s the energy currency of cells. 
  • The combustion of gasoline in car engines releases energy that powers the vehicle’s movement.

These reactions decrease free energy and can be joined with endergonic reactions to provide energy for non-spontaneous processes. For example, ATP hydrolysis is an exergonic reaction that releases energy and drives endergonic processes, such as active transport.

The concept of exergonic reactions was understood centuries ago, long before it was formally defined in modern science. Early humans discovered fire and used its heat energy. That’s an exergonic reaction at work.

Release of free energy in exergonic reactions

Exergonic reactions release free energy, making it useful for cellular processes. Reactants’ potential energy is transformed into kinetic energy, giving organisms plenty of energy to use.

This free energy is essential for various bodily functions. It fuels ATP production, and helps make macromolecules like proteins and nucleic acids. Plus, exergonic reactions help maintain homeostasis. They provide energy for muscle contraction and nerve impulse transmission. The cyclic nature of these reactions ensures a steady supply of energy.

Understanding exergonic reactions can help researchers enhance metabolism and develop medical treatments.

Endergonic reactions

To understand endergonic reactions, let’s dive into two key aspects: the definition and examples of endergonic reactions and the absorption of free energy in these reactions. Endergonic reactions involve the input of energy to proceed and are characterized by an increase in Gibbs free energy. By examining specific cases and exploring the energy dynamics involved, we can gain insights into how endergonic reactions differ from other types of chemical reactions.

Definition and examples of endergonic reactions

Endergonic reactions require more energy than they give out. Photosynthesis and protein synthesis are examples. In photosynthesis, plants take sunlight and turn it into energy. During protein synthesis, energy in the form of ATP is needed to join amino acids.

Exergonic vs Endergonic

Photosynthesis as an example of Endergonic reaction

Coupling endergonic reactions with exergonic reactions is possible. That’s what happens during cellular respiration  ATP hydrolysis supplies the energy.

To increase the rate of endergonic reactions, 

  • We can increase the concentration of reactants. 
  • We can also raise the temperature or add a catalyst like enzymes. 
  • Enzymes help lower the energy needed for the reaction to occur.

Endergonic reactions can be useful. We can use them in many fields like biochemistry and industrial manufacturing. We just need to learn how to optimize and use the resources around us.

Absorption of free energy in endergonic reactions

Endergonic reactions are energy-absorbing. They require energy from the environment to take place. This is essential for cell activities. Chemical bonds break and form, so energy is required to reach a state of equilibrium. We can see this in photosynthesis plants that turn CO2 and water into glucose and oxygen, using sunlight and chlorophyll.

Understanding endergonic reactions is key for scientists in fields like biochemistry and pharmacology. With this insight, it’s possible to create better drugs and more efficient technologies. Exergonic reactions make things go ‘boom’, while endergonic reactions make things go ‘meh’.

Difference between exergonic and endergonic reactions

To understand the difference between exergonic and endergonic reactions, let’s dive into the energy changes involved and the concept of Gibbs free energy. In the first subsection, we’ll explore how energy is affected in exergonic and endergonic reactions. Then, we’ll delve into the role of Gibbs free energy in determining whether a reaction is spontaneous or not. By examining these aspects, we can grasp the distinction between exergonic and endergonic reactions.

Energy changes in exergonic and endergonic reactions

Exergonic reactionsEndergonic reactions
Exergonic reactions occur when the products possess less energy than the reactants. As a result, energy is released, often in the form of heat or light. This energy drives many vital processes in living organismsEndergonic reactions need an input of energy. The products of these reactions possess a higher potential energy than the reactants. This energy is usually obtained from exergonic reactions or external sources, like sunlight.
Examples: the breakdown of glucose during cellular respiration, combustion of fuels and muscle contractions and nerve impulsesEndergonic reactions are involved in energy-requiring processes, like photosynthesis, where plants turn light energy to chemical energy stored in glucose.

It’s noteworthy that exergonic and endergonic reactions are linked within biological systems. The energy released by exergonic reactions fuel endergonic reactions by providing the necessary energy. This balance between exergonic and endergonic processes allows organisms to maintain homeostasis and carry out essential functions.

Pro Tip: Knowing the difference between exergonic and endergonic reactions is vital in fields such as biochemistry and biology. This knowledge can help researchers design effective chemical pathways or create new ways to use energy for various applications. 

Gibbs free energy and spontaneous reactions

Gibbs free energy and spontaneous reactions are essential for comprehending the spontaneity of chemical reactions. We can determine if a reaction will take place spontaneously by analyzing its energetics.

For example, look at this table:

ReactantProductGibbs Free Energy Change (∆G)
AB-20 kJ/mol
CD+10 kJ/mol
EF+30 kJ/mol

From this table, we can witness the shift in Gibbs free energy (∆G) for different reactions. A negative ∆G, like A to B (-20 kJ/mol), shows the reaction is exergonic and releases energy. Whereas, a positive ∆G such as E to F (+30 kJ/mol) means the reaction is endergonic, needing energy to happen.

It’s essential to bear in mind that, although a negative ∆G implies spontaneity, it doesn’t necessarily mean the reaction will take place quickly. Activation energy and reaction rates also influence the eventuality of a reaction.

So, to comprehend the idea of Gibbs free energy and spontaneous reactions, it’s critical to understand how these values are calculated and interpreted in distinct chemical processes. By studying more, you’ll get insight into how chemical reactions naturally take place and how they can be regulated or manipulated.

Applications of exergonic and endergonic reactions

To understand the practical implications of exergonic and endergonic reactions, let’s delve into their applications. In biological reactions, ATP plays a crucial role as an energy currency, and we’ll explore how it relates to exergonic and endergonic reactions. Additionally, we’ll dive into metabolic reactions and how energy is transferred within living organisms. These real-world examples will shed light on the importance and functioning of exergonic and endergonic reactions in various biological processes.

Biological ReactionsATP
Energy productionYes
Metabolic processesYes
Cellular respirationYes

Biological reactions and ATP are key players in metabolic processes, such as DNA replication, protein synthesis, and cell signaling. ATP is also essential for cellular respiration, the process where cells convert glucose into usable energy. This happens in the mitochondria, with ATP made through oxidative phosphorylation.

ATP is nicknamed the “molecular unit of currency” for its role in storing and transferring energy. One molecule of ATP breaks down into ADP (adenosine diphosphate) and a phosphate group, then releases energy for biochemical reactions.

It’s estimated that an adult human generates their body weight in ATP daily! This shows how important biological reactions and ATP are for cellular functions.

Metabolic reactions and energy transfer

Exergonic reactions, like cellular respiration, release energy as a byproduct of breaking down organic molecules. On the other hand, endergonic reactions, such as photosynthesis, need energy to create complex organic compounds.

Metabolism is key to transforming macronutrients into energy for the body. Carbohydrates are broken down into ATP, which cells use as energy.

A balanced diet and regular physical activity are necessary for optimal metabolic reactions and energy transfer. Eating a variety of macronutrients and exercising stimulates metabolic pathways and helps maintain a balance between exergonic and endergonic processes.

Factors influencing the direction of exergonic and endergonic reactions

To determine the direction of exergonic and endergonic reactions, several factors come into play. Concentrations of reactants and products, alongside temperature and pressure conditions, play a crucial role. By examining these variables, we can understand how they influence the spontaneity and feasibility of these reactions. Factors such as the relative concentrations of reactants and products and the specific temperature and pressure conditions create an environment that either drives or hinders the reaction’s progression.

Concentrations of reactants and products

In chemical reactions, concentrations of reactants and products have a big impact on exergonic and endergonic reactions. Reactant concentration means the amount of substances available to react. Product concentration is the amount of substances made as a result of the reaction.

The table below shows the concentrations of reactants and products and their effect on the reaction direction:

Reactant ConcentrationProduct ConcentrationEffect on Reaction Direction
HighLowForward (exergonic)
LowHighReverse (endergonic)

The table above shows us that when reactant concentration is high and product concentration is low, it leads to a forward reaction (exergonic). On the other hand, if the reactant concentration is low and product concentration is high, the reaction goes in reverse (endergonic). Both concentrations being equal creates an equilibrium, where both forward and reverse reactions occur at the same rate.

Temperature can also influence reaction direction. Higher temperatures boost reaction rates by providing more energy. So, the right temperature can help make sure reactions go in the desired direction.

It’s very important to control reactant and product concentrations to get the desired outcomes from reactions and to increase efficiency. 

Temperature and pressure conditions

Temperature and pressure can affect exergonic and endergonic reactions in various ways. 

  • Temperature increases the rate of exergonic reactions, while endergonic ones may slow down or become inhibited. 
  • Pressure affects gaseous reactions, increasing the chance of collisions and possibly altering equilibrium constants.

These effects are not absolute for all reactions and may differ depending on the chemical system. When manipulating temperature or pressure, it is important to maintain safety and follow protocols for accurate results. To get desired reaction outcomes, chemists must master the factors influencing reaction direction. 

Frequently Asked Questions

Q: What are endergonic and exergonic reactions?

A: Endergonic and exergonic are terms to describe the direction of a reaction based on the change in free energy. Endergonic reactions require an input of energy to proceed, whereas exergonic reactions release energy.

Q: What is the difference between endergonic and exergonic reactions?

A: The main difference between endergonic and exergonic reactions lies in the change of free energy. Endergonic reactions have a positive delta G, while exergonic reactions have a negative delta G. Endergonic reactions require energy to proceed, while exergonic reactions release energy.

Q: What is Gibbs free energy?

A: The Gibbs free energy is a thermodynamic property that measures the amount of energy available to do work in a system at constant temperature and pressure. It is represented by the symbol G.

Q: What is the difference between endergonic vs exergonic reactions?

A: Endergonic reactions absorb energy from their surroundings in order to proceed, while exergonic reactions release energy to their surroundings.

Q: What is the relationship between entropy and endergonic vs exergonic reactions?

A: Entropy is a measure of disorder in a system. Endergonic reactions typically have a lower entropy than the reactants, while exergonic reactions have a higher entropy than the reactants.

Q: What is a reverse reaction?

A: A reverse reaction is the reaction that occurs when the products of a reactant reaction are converted back into the original reactants.

Q: What is an exothermic reaction?

A: An exothermic reaction is a chemical reaction that releases energy, usually in the form of heat, to its surroundings.

Q: What is an endothermic reaction?

A: An endothermic reaction is a chemical reaction that absorbs energy, usually in the form of heat, from its surroundings.

Q: What is chemical equilibrium?

A: Chemical equilibrium occurs when the rate of the forward reaction is equal to the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products.

Q: What is the standard Gibbs free energy?

A: The standard Gibbs free energy is the Gibbs free energy change that occurs when all reactants and products are in their standard states at a given temperature and pressure.


Exergonic and endergonic reactions differ in their free energy output. Exergonic reactions have a negative ∆G, indicating the products have lower free energy than the reactants. This leads to the reaction releasing energy and proceeding spontaneously. Examples of exergonic reactions include combustion and cellular respiration. Endergonic reactions, however, have a positive ∆G, with the products having higher free energy than the reactants. These reactions need an input of energy in order to proceed and are non-spontaneous under standard conditions. Photosynthesis is one example of an endergonic reaction. In summary, exergonic reactions release energy, while endergonic reactions absorb energy. Entropy and enthalpy are both important to consider when attempting to understand these concepts.

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