When chemical bonds are broken and new ones are formed during a chemical reaction, there is a transfer of energy. The energy changes that occur during a chemical reaction are governed by the principles of thermodynamics. There are two main types of energy changes that can occur:
Endothermic Reaction:
In an endothermic reaction, energy is absorbed from the surroundings.
Energy is required to break the existing bonds in the reactants, which is an endothermic process.
Energy is released when new bonds are formed in the products, which is an exothermic process.
The overall effect is that the products have higher potential energy than the reactants.
Endothermic reactions typically feel cold to the touch because they absorb heat from the surroundings.
Exothermic Reaction:
In an exothermic reaction, energy is released into the surroundings.
Energy is required to break the existing bonds in the reactants, which is an endothermic process.
Energy is released when new bonds are formed in the products, which is an exothermic process.
The overall effect is that the products have lower potential energy than the reactants.
Exothermic reactions typically feel hot to the touch because they release heat into the surroundings.
In summary, energy is conserved during a chemical reaction, but it can change forms. Breaking chemical bonds requires an input of energy (endothermic), and forming new chemical bonds releases energy (exothermic). Whether a reaction is endothermic or exothermic depends on the overall energy balance between these two processes.