Difference Between Endothermic Reactions and Exothermic Reactions
Main Difference
The main difference between endothermic reactions and exothermic reactions is that endothermic reaction is a type of reaction in which heat is absorbed from the surrounding while the exothermic reaction is the reaction in which heat is released into the surrounding.
Endothermic Reactions vs. Exothermic Reactions
On the basis of energy or heat, the chemical reactions are classified into two main types, i.e., endothermic reactions and exothermic reactions. Endothermic reactions are those reactions that absorbed energy in the form of heat from the environment whereas exothermic reactions released energy into the surrounding. So, energy will have to be provided in case of an endothermic reaction, but the exothermic reaction does not require energy. In an endothermic reaction, the substrate has less energy than product while in exothermic reactions, the substrate has more energy as compared to the product. This change in energy during different reactions is called heat of reaction and known as enthalpy. It is denoted by ‘ΔH‘ and expressed in kJ/mol.
Comparison Chart
| Endothermic Reactions | Exothermic Reactions |
| A reaction in which system absorbs energy from the environment is called endothermic reaction. | A reaction in which system release energy into the environment is called exothermic reaction. |
| Meaning | |
| Endothermic is derived from the Greek word where “Endo” means “inside” while “Thermic” means “heat.” | Exothermic is derived from a Greek word where “Exo” means “outside” while “Thermic” means “heat.” |
| Energy Requirement | |
| Endothermic reactions require energy to complete. | Exothermic reactions do not require energy. |
| Reactants and Products | |
| Endothermic reactions have low energy reactants but high energy products. | Exothermic reactions have high energy reactants but low energy products. |
| Environment | |
| The endothermic reaction makes the surroundings cool by absorbing energy. | The exothermic reaction makes the surroundings hot by releasing temperature. |
| Form of Energy | |
| Energy is absorbed in an endothermic reaction. | In exothermic reactions, energy is usually released in the form of heat, but can also be in the form of electricity, light or sound. |
| Enthalpy (ΔH) | |
| ΔH is positive in an endothermic reaction because heat is absorbed. | ΔH is negative in an exothermic reaction, as heat is evolved. |
| Application | |
| It has applications in thermodynamics; physics, chemistry. | It is also used in thermodynamics; physics, chemistry. |
| Examples | |
| Photosynthesis, reacting ethanoic acid with sodium carbonate | Explosions, rusting iron, burning of coal, chemical bonds, nuclear fission, and fusion are examples of exothermic reactions. |
What are Endothermic Reactions?
The word endothermic is derived from a Greek word in which “Endo” means “inside” while “Thermic” refers to “heat,” So, an endothermic reaction is the reaction in which heat is absorbed from the surroundings. Heat is to be supplied in case of an endothermic reaction. Two or more molecules or reactants react in the presence of heat to make the product. So, it cools the surrounding environment by absorbing energy through it. Moreover, it stores the energy in the form of chemical bonds of the product. Therefore, in the case of an endothermic reaction, the product has more energy than reactants. It has applications in thermodynamics; physics, chemistry. Moreover, the value of ΔH is always positive because of heat absorption during the reaction.
Example
Photosynthesis is a type of an endothermic reaction in which chlorophyll use carbon dioxide plus water and energy from sunlight to produce glucose and oxygen.
What are Exothermic Reactions?
The word exothermic is derived from a Greek word in which, “exo” means “outside” while “Thermic” refers to “heat” So, the exothermic reaction is the reaction in which heat is released into the surroundings. Heat is released in the case on exothermic reaction. Sometimes it is harmful if the reaction is occurring at a higher rate. Two or more molecules react to form a product by releasing energy. So as a result, it increases the temperature of the surrounding environment. Therefore, in the case of an exothermic reaction, reactants have more energy than the product. It also has applications in thermodynamics; physics, chemistry. During the exothermic reaction, the value of ΔH is always negative due to the release of energy.
Example
Its example is a campfire in which heat is released from the chemical bonds of paper and wood in the form of light and heat and warms the sitter present around it.
Key Differences
Conclusion
From the above discussion, it is concluded that an endothermic reaction is a reaction that absorbs heat and stores it in the chemical bonds of its product, e.g., photosynthesis while the exothermic reaction is the reaction that releases the stored energy of its reactants into the surroundings, e.g., campfire
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