Answer:
An exothermic reaction and an endothermic reaction are two types of chemical reactions that differ in terms of the energy they release or absorb:
1. **Exothermic Reaction:**
- In an exothermic reaction, energy is released into the surroundings in the form of heat or light.
- The reactants have a higher amount of energy compared to the products. As the reaction progresses, this excess energy is released, leading to a decrease in the total energy of the system.
- Exothermic reactions typically feel warm to the touch and may produce light or sound. Examples include combustion reactions (burning), such as the burning of gasoline or wood.
2. **Endothermic Reaction:**
- In an endothermic reaction, energy is absorbed from the surroundings, causing a decrease in temperature.
- The reactants have a lower amount of energy compared to the products. As the reaction proceeds, energy is absorbed from the surroundings to raise the energy level of the system.
- Endothermic reactions feel cold to the touch and require an external source of heat to occur. Examples include many chemical reactions used in cold packs or instant cold packs, where the reaction absorbs heat from the environment.
In summary, the key difference lies in the direction of energy flow:
- Exothermic reactions release energy to the surroundings, resulting in an increase in temperature.
- Endothermic reactions absorb energy from the surroundings, causing a decrease in temperature.