¶¶¶Endothermic and exothermic reactions are chemical reactions that absorb and release heat, respectively. A good exampleof an endothermic reaction is photosynthesis. Combustion is an exampleof an exothermic reaction. ... In any givenreaction, heat is both absorbed and released....

Exothermic and Endothermic Reactions
Exothermic and endothermic reactions are two types of chemical reactions that involve the release or absorption of energy, respectively.

Exothermic Reaction
An exothermic reaction is a chemical reaction that releases energy in the form of heat. This means that the products of the reaction have less energy stored in their chemical bonds than the reactants. As a result, the excess energy is given off as heat to the surroundings. Some examples of exothermic reactions include:
1. Combustion reactions: Burning of wood, coal, or gasoline releases heat energy.
2. Neutralization reactions: Mixing an acid and a base to form water and a salt releases heat.
3. Decomposition reactions: Breaking down hydrogen peroxide into water and oxygen releases heat.
4. Oxidation reactions: Rusting of iron is an exothermic reaction.

Endothermic Reaction
On the other hand, an endothermic reaction is a chemical reaction that absorbs energy from the surroundings. In this type of reaction, the products have more energy stored in their chemical bonds than the reactants. As a result, energy is taken in from the surroundings. Some examples of endothermic reactions include:
1. Photosynthesis: Absorption of sunlight by plants to convert carbon dioxide and water into glucose and oxygen.
2. Dissolution of ammonium nitrate in water: This reaction absorbs heat, causing the solution to cool down.
3. Thermal decomposition of calcium carbonate: Heating calcium carbonate to produce calcium oxide and carbon dioxide absorbs heat.
In conclusion, exothermic reactions release heat energy to the surroundings, while endothermic reactions absorb heat energy. Both types of reactions play a crucial role in various chemical processes and are essential to understanding the behavior of matter in the universe.