Exothermic Reaction

Chemistry is all about reactions. Exothermic reactions are the reactions in which energy in the form of heat is released during the reaction between two reactants. The temperature of the reaction mixture increases during these reactions. In the process of an exothermic reaction, the energy is released due to the formation of bonds between the reactants to form the products. These types of reactions are observed in matchsticks, firecrackers, the composting process of waste, the release of water vapour from a teapot, and many more.

Definition of a reaction in the field of chemistry

A chemical reaction is a process that converts one or more compounds, which are known as reactants, into one or more distinct substances, which are known as products. Substances can be classified as chemical elements or compounds. A chemical reaction restructures the atoms of the reactants to produce various products.

Examples of reactions in chemistry

• Decomposition Reactions
• Combination Reactions
• Displacement Reactions
• Double Displacement Reactions
• Precipitation Reactions
• Neutralisation Reactions
• Exothermic Reactions
• Endothermic Reactions

What is an exothermic reaction in chemistry?

An exothermic reaction is a reaction or process in which energy is released in the form of light or heat. These reactions are the reverse of endothermic reactions and may be stated as:

Reactant → Products + Heat Energy/ Light Energy

In simple words, an exothermic process is one that releases energy in the form of light or heat. Thus, in an exothermic reaction, some amount of energy is transmitted into the environment rather than being absorbed from it, like what happens in an endothermic reaction. The enthalpy change (which is denoted by ΔH) in an exothermic process will be negative because of the release/loss of energy.

The net amount of energy required to launch an exothermic reaction is less than the net amount of energy produced by the reaction. The net quantity of heat energy that passes through a calorimeter is equivalent to the negative of the overall energy change that takes place in the system.

However, calculating the exact amount of energy in a specific chemical system is challenging. Therefore, the change in energy (enthalpy change, represented by ΔH) is calculated instead. The following equation describes the relationship between the value of H and the reaction’s bonding energy.

ΔH = energy utilised to form the bond that yields the products – energy that is given out when the bonds between the reactants are hampered.

Exothermic reactions are those that produce energy. When bonds are formed in the products, more energy is released than is used to split the bonds in the reactants in exothermic reactions.

Examples of exothermic reactions

Exothermic reactions are chemical processes that produce heat or light as a result. Exothermic reactions are almost likely to occur all around us. 

Instances of exothermic reactions may be found anywhere, from lighting a candle to the nuclear fusion process in the sun. Some of the exothermic processes that occur around us and in chemistry are:

• Combustion of Glucose : C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy

• Combustion of Methane : CH4 + O2 → CO2 + H2O + Heat

• Dissociation Of Carbon Monoxide : CO (g) → C (g) + O (g) + Energy

• Lighting a matchstick
• The common festival fireworks
• Coals burnt on a barbeque
• Vinegar treating an alkaline sting
• Compost neutralising the acids that are present in the soil
• Antacids neutralising the acid in the stomach
• Condensation of water vapour into rainwater
• Acid being dissolved in water

These examples are exothermic reactions because they produce heat energy rather than consuming it. Heat is required for reversal reactions, such as melting an ice cube or water being converted to steam. As a result, the reversal reactions are endothermic.

Measuring exothermic reaction

Calorimeters, which detect extremely tiny quantities of heat, are used by scientists to evaluate if a process is exothermic or not. If a reaction produces heat energy, it will be warmer than the air present in the environment. Energy level diagrams can also be used to visualise the energy change that occurs throughout a chemical reaction due to the forms of energy used and released.

Conclusion

Thus, we can conclude that exothermic reactions are associated with the release of energy due to the formation of bonds between the reactants to form products. Calorimeters, which detect extremely tiny quantities of heat, are used by scientists to evaluate if a process is exothermic or not.

In our day-to-day lives, we observe exothermic reactions from the above examples. Exothermic reactions are the opposite of endothermic reactions, in which the energy is given to break the bonds between reactants. Thus, the exothermic reaction questions now can be answered easily by using the exothermic reaction notes above.