Examples of exothermic reactions in everyday life
A thermochemical reaction shows the conversion of reactants to products with the information of energy change and physical state of the involved species. On the basis of energy change; reaction can be classified in two types.
One is exothermic and another is endothermic reaction. An endothermic reaction is preceded with the absorption of heat by reactant molecules.
The absorption of reactant molecules increases the energy level of product molecules. The absorption of energy by reactant molecules can be shown in the terms of change in enthalpy (ΔH).
For endothermic reactions; the value of change in enthalpy would be +ve otherwise for exothermic reaction; it will be –ve value. This is due to liberation of energy in the form of heat during exothermic reaction.
The energy level of products is less compare to reactant molecules.
Overall an exothermic chemical reaction is described as the evolution of heat during reaction.
The reaction equation can be written as given below;
Reactant molecules → Products + Heat (Energy)
An exothermic reaction is a favourable process as the energy level of product molecules is less compare to reactants.
The less energy helps in the stabilization of molecules.
Hence exothermic reactions are thermodynamically favourable reactions and usually spontaneous in nature. Let’s discuss some common examples of exothermic reaction which we can observe in our everyday life.
The condensation of water vapor in cloud which results the formation of rain water is an example of exothermic reaction. Similarly the cement and concrete setting or setting of epoxy resin is also same type of reactions.
The combustion of fuels such as hydrocarbons results the formation of carbon dioxide gas with water vapor releases a large amount of energy in the form of heat.
The dissolution of organic or inorganic acids in water also liberates some energy which can varies from acid to acid such concentrated H2SO4 releases a large amount of heat while acetic acid is a weak acid which cannot release same amount of heat during formation of aqueous solution. Formation of aqueous solution of anhydrous salts such as anhydrous copper sulphate or calcium chloride also releases some amount of heat in the form of energy.
The mixing of sodium sulphite with bleach or crystallization of liquid salts is also an exothermic reaction.
You must hear about neutralization reaction of acid-base which results the formation of neutral salts is an exothermic reaction.
The amount of heat for this reaction is a constant value which is - 57 kJ mol-1.
The thermite reaction of Al metallurgy and polymerisation reactions for the manufacturing of polymers are also releasing some energy in the form of heat. The oxidation of metals or other organic compounds also an example of exothermic reaction.
The nuclear reaction mainly nuclear fission is an exothermic reaction.
The formation of ice from water or formation of snow, etc. is some of the prominent examples of same type of reaction.
Even the burning of candle is also such type of reaction.
Usually these reactions are spontaneous reactions which do not require any external force to carry out these reactions. But remember these reactions are not always exothermic in nature; can be endothermic also.