What is the Difference Between Endothermic and Exothermic Reactions?
🆚 Go to Comparative Table 🆚The main difference between endothermic and exothermic reactions lies in the heat energy that is absorbed or released during the reactions. Here are the key differences:
- Endothermic Reactions:
- Absorb heat energy from the surroundings.
- The temperature of the system decreases, as heat is taken up from the surroundings.
- The enthalpy of the system increases, indicating that more energy is absorbed when the bonds in the reactants are broken than is released when new bonds are formed.
- Examples include photosynthesis and the reaction between ammonium nitrate and water.
- Exothermic Reactions:
- Release heat energy into the surroundings.
- The temperature of the system increases, as heat is released to the surroundings.
- The enthalpy of the system decreases, indicating that more energy is released when the products are formed than the energy used to break up the reactants.
- Examples include the reaction between sodium and chlorine and the formation of water from hydrogen and oxygen.
In summary, endothermic reactions absorb heat energy from the surroundings, resulting in a decrease in temperature, while exothermic reactions release heat energy into the surroundings, leading to an increase in temperature.
Comparative Table: Endothermic vs Exothermic Reactions
Here is a table comparing the differences between endothermic and exothermic reactions:
Feature | Endothermic Reactions | Exothermic Reactions |
---|---|---|
Energy Absorption or Release | Absorbs energy from the surroundings | Releases energy into the surroundings |
Temperature Effect | Causes a cooling effect by lowering the temperature of the surrounding environment | Causes a heating effect by raising the temperature of the surrounding environment |
Enthalpy Change (ΔH) | Positive, i.e., ΔH > 0 | Negative, i.e., ΔH < 0 |
Bond Formation/Breaking | Breaking bonds requires energy, and new bonds are formed as a result of heat absorption | New bonds are formed, releasing energy in the process |
Examples | Photosynthesis, evaporating liquids, melting ice, dry ice, alkane cracking, thermal decomposition, ammonium chloride in water | Combustion reactions, respiration, and the formation of many chemical compounds from their elements |
Endothermic reactions absorb energy from the surrounding environment, usually in the form of heat, causing a decrease in the temperature of the system. On the other hand, exothermic reactions release energy into the surroundings, resulting in an increase in temperature.
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