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Endothermic Reaction – Definition, Equation, Examples, Formula

Endothermic Reaction: When a chemical link is broken, energy is normally released in the process. The creation of chemical bonds, too, necessitates an energy input. The energy that is supplied/released can take many different forms (such as heat, light, and electricity). Endothermic reactions are characterised by the creation of chemical bonds as a result of heat absorption from the environment. Exothermic reactions, on the other hand, involve the release of heat energy generated by bond-breakage.

Endothermic Reaction

Endothermic reactions are chemical processes in which the reactants absorb heat from the environment to produce products. These reactions cause a cooling effect by lowering the temperature of the surrounding environment. Ice cubes absorb heat energy from their surroundings and melt to generate liquid water, which is an endothermic process.

Endothermic Reaction: Definition

A chemical process that is generally accompanied by the retention of warmth (or heat), or a living being that creates warmth (or heat) to maintain its temperature, is known as an endothermic reaction. A chemical process that operates only if heat is retained is an example of an endothermic reaction. A warm-blooded animal, such as humans, is an example of an endothermic mammal.

Endothermic processes require energy from the surrounding environment, preferably in the form of heat, in order to occur. Because endothermic processes absorb heat from their surroundings, they will produce a slight drop in temperature in their surroundings. They’re also non-spontaneous since endothermic reactions produce products that have more energy than the reactants. As a result, the enthalpy adjustment for an endothermic process is always positive. Heat is necessary for a chemical reaction involving the dissolution of ice, hence the process is endothermic. The concept is also commonly employed in physical disciplines, such as in chemical reactions, where warm energy (heat) is converted to chemical bond energy.

Endothermic Reaction: Equation

Reactants + Energy  —> Products

is the general equation for an endothermic reaction. Note that H stands for energy change. The temperature of the products in endothermic reactions is usually lower than the temperature of the reactants.

Melting ice cubes, solid salts, liquid water evaporation, and frost to water vapour conversion (melting, boiling, and evaporation are all endothermic processes).

Endothermic Reaction: Formula

In photosynthesis, plants are make the simple sugar glucose (C6H12O6) from carbon dioxide (CO2) and water (H2O). They also release oxygen (O2) in the process. The reactions of photosynthesis are summed up by.

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Endothermic Reaction: Examples

  • Sublimation of solid CO2
  • Evaporation of liquid water, formation of water vapour.
  • The baking of bread.
  • The melting of ice to form water.

To keep cool, the human body uses the endothermic characteristic of evaporation. Sweating serves as a means of accomplishing this. Sweat (formed on the skin’s surface) absorbs heat from the skin and evaporates, resulting in a cooling effect.

Sweating, on the other hand, is not an exothermic response. Existing chemical bonds can be broken, new chemical bonds can be formed, or both can happen in a chemical reaction. Sweat evaporation does not result in any chemical changes, but it does result in a physical phase shift (from liquid to vapour). As a result, evaporation is classified as a physical rather than an endothermic reaction.

Endothermic Reaction vs. Exothermic Reaction

The phrases ‘Endo’ and ‘Exo,’ which imply ‘inside’ and ‘out,’ respectively, have Greek roots. The major difference between endothermic and exothermic reactions, as their names suggest, is that the former absorbs heat from the environment while the latter releases it.

An endothermic process is one that absorbs heat from its environment. As a result, all endothermic reactions and processes are endothermic. The opposite, however, is not true. Physical rather than chemical changes are involved in many endothermic reactions.

1. The system absorbs heat from the surroundings The system releases heat into the surroundings
2. The entropy of the surrounding decreases, i.e.

=>  ΔS <0

Entropy of the surrounding increases, i.e.

=>  ΔS>0

3. Enthalpy change (ΔH) is positive Enthalpy change (ΔH) is negative

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Endothermic Reaction: FAQs

Q. What are three examples of an endothermic reaction?

Ans. Melting ice cubes, melting solid salts, and sublimation of dry ice into carbon dioxide gas are three instances of endothermic reactions.

Q. What is endothermic reaction give one example?

Ans. Endothermic reaction is a chemical reaction in which heat is absorbed. Temperatures drop as a result of it. e.g. Nitric oxide gas is generated when nitrogen and oxygen are heated to a temperature of around 3000°C.

Q. What are endothermic and exothermic reaction?

Ans. The temperature of the immediate surroundings rises as an exothermic process releases heat. An endothermic process absorbs heat from the environment and cools it.

Q. What type of reaction occurs in handwarmer?

Ans. In hand warmers, the chemical reaction is exothermic, which means it releases surplus energy as heat. As a result, you can warm your hands by combining a few chemicals.

Q. Why self heating cans can only be used once?

Ans. Because the metal at the bottom of the can is coated with a heat-sensitive substance that reacts when it comes into touch with food or drink, the self-heating can only be utilised once. The reaction initiates oxidation, a chemical reaction that causes the metal to dissolve and rust.

Q. What happens when you put hand warmers in water?

Ans. A hand warmer is made up of sodium acetate that has been dissolved in water. The solution has been heated to dissolve more sodium acetate, making it’super-saturated.’ The solution rapidly crystallises.


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