What is an exothermic reaction
An exothermic reaction is a reaction in which energy is released in the form of light or heat. Thus in an exothermic reaction, energy is transferred into the surroundings rather than taking energy from the surroundings as in an endothermic reaction. In an exothermic reaction, change in enthalpy ( ΔH) will be negative.
Exothermic reaction examples
Exothermic reactions are everywhere, from the burning of a candle to our burning sun. Let us look at some of the common exothermic reaction examples in everyday life.
- Combustion: We know combustion to be the burning of carbon containing compounds in the presence of oxygen which gives out a lot of energy as heat and other by products. One such example of combustion would be the combustion of methane which can be represented as: CH4 + O2 ->CO2 + H2O + Heat
- Detonation of nitroglycerin: The explosive power of nitroglycerin derives from detonation. Detonation of nitroglycerin generates gases that would occupy more than 1,200 times the original volume at ordinary room temperature and pressure. From the amount of heat liberated, the temperature can increase upto 5,000 °C (9,000 °F).
- Nuclear fission of uranium-235: The process of nuclear fission is a case of either radioactive decay or nuclear reaction wherein an atom’s nucleus splits into lighter nuclei components. The process produces a large amount of energy. This is used to power nuclear power plants.
- Neutralisation reactions: We know a neutralization reaction to be a reaction wherein the reactants are an acid and base which combine to form a salt and water molecule. This neutralizes the pH of the reaction. The combining H+ and OH ions have a standard enthalpy change for the reaction of −57.30 kJ/mol. Hence a neutralization reaction becomes exothermic.
Why is respiration an exothermic reaction ?
Respiration is the process by which us humans take in oxygen and give out energy and carbon dioxide. The chemical equation of this process can be represented as: C6H12O6 + 6O2 →6CO2 + 6H2O + Energy
Glucose – C6H12O6
Oxygen – O2
Carbon Dioxide – CO2
Water – H2O
This energy produced make respiration an exothermic reaction.
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