Question

What is an exothermic reaction? Explain with two examples.

Answer 1

1. The reaction in which the evolution of heat is experienced is called an exothermic reaction, which is generally the result of a spontaneous process.
2. Or in other words, it can also be stated as a chemical reaction where the total heat content of the reactant is more than that of the product.
3. For example:$\underset{\left(\mathrm{Methane}\right)}{\underbrace{{\mathrm{CH}}_4\left(\mathrm{g}\right)}}+\underset{\left(\mathrm{Oxygen}\right)}{\underbrace{{\mathrm{O}}_2\left(\mathrm{g}\right)}}\to \underset{(\mathrm{Carbon}\mathrm{dioxide})}{\underbrace{{\mathrm{CO}}_2\left(\mathrm{g}\right)\uparrow }}+\underset{\left(\mathrm{Water}\right)}{\underbrace{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}}+\mathrm{heat}$
4. Here in this reaction Methane undergoes a combustion reaction to produce Carbon dioxide $\left({\mathrm{CO}}_2\right)$ and Water $\left(H_{2}O\right)$ and heat.
5. $\underset{(\mathrm{Zinc}\mathrm{sulphide})}{\underbrace{\mathrm{Zn}\left(\mathrm{s}\right)}}+\underset{(\mathrm{Sulphuric}\mathrm{acid})}{\underbrace{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}}\to \underset{(\mathrm{Zinc}\mathrm{sulphate})}{\underbrace{{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)}}+\underset{(\mathrm{Hydrogen}\mathrm{gas})}{\underbrace{{\mathrm{H}}_2\left(\mathrm{g}\right)\uparrow }}+\mathrm{Heat}$
6. Here, in this reaction hydrogen is getting displaced by zinc to produce Zinc sulphate $\left({\mathrm{ZnSO}}_4\right)$ and hydrogen $\mathbf{\left(}{\mathbf{H}}_{\mathbf{2}}\mathbf{\right)}$ and heat.