Question

Explain energy changes in a chemical change.

Answer 1

The energy changes happen due to the formation or breaking of bonds. Some reactions are known as exothermic, in which energy is released. And some are known as endothermic, in which energy is consumed.
Complete answer:
When there is some breakage of chemical bonds the energy is absorbed and when there is formation of bond the energy is released, chemical reactions in one way or the other involves a change of energy between their products and reactants. We know that energy can neither be created nor be destroyed. So the scientists have formulated a law of conservation of energy where the total energy of the system must remain unchanged and many times there will either be absorption or release of energy in the form of heat, light etc. This change of energy is mainly due to the difference between the amount of energy in product and reactant. This stored energy is known as the enthalpy of the system. Let’s talk about some of the type of reactions:
-Exothermic reaction: These reactions give out heat and light to their surroundings. For example, combustion reaction. The internal energy of products is less than that of reactants which is why exothermic reactions have negative enthalpy of reaction. Which means we don’t need too much energy to break the bonds of the reactants and it is still less than the energy released when the bond is formed.
-Endothermic reaction: These reactions absorb heat and light from their surroundings. For example, decomposition reaction. The internal energy of products is more than the reactants. This is why the enthalpy of endothermic reaction is said to be positive. Which means that energy required to break the bonds is more than the energy used in forming of the bonds

Note:
Energy, in simple language, is the capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. There are, moreover, heat and work—i.e., energy in the process of transfer from one body to another.