Question

Distinguish between exothermic and endothermic reactions.

Answer 1

Distinguish between exothermic and endothermic reactions:

Exothermic reaction

Endothermic reaction

During a chemical reaction, the heat evolved from the substance of the system to the surrounding is known as an exothermic reaction. Products have less energy than reactants. When carbon burns in oxygen to make carbon dioxide$\underset{\mathrm{carbon}}{\mathrm{C}\left(\mathrm{g}\right)}+\underset{\mathrm{oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\mathrm{Heat}\mathrm{energy}$, Temperature increases during a chemical reaction. The evolution of heat is spontaneous. Products are more stable. Examples: Rusting iron, nuclear fission, explosions, etc.

During a chemical reaction, heat is absorbed by the substance of the system from the surrounding is known as an Endothermic reaction. Products have more energy than reactants. Carbon reacts with water and by providing heat we get carbon monoxide.$\underset{\mathrm{carbon}}{\mathrm{C}\left(\mathrm{s}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\stackrel{\mathrm{heat}}{\to }\underset{\mathrm{carbon}\mathrm{monoxide}}{\mathrm{CO}\left(\mathrm{g}\right)}+\underset{\mathrm{hydrogen}\mathrm{gas}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$ Temperature decreases during a chemical reaction. The absorption of heat is non-spontaneous. Products are less stable. Examples: Melting ice, evaporation, cooking, photosynthesis, etc.