Energy of Activation in a chemical reaction

Question :

What do understand by Exergonic and Endergonic chemical reaction and Energy of Activation?

Energy of Activation:

Mostly metabolic reactions needs an initial input of energy to proceed a chemical reaction. This amount of energy is called activation energy.

Types of Reactions:

There are two types of reactions

1. Exergonic reactions

2. Endergonic reactions

  1. Exergonic Reactions:

In this type of reactions, net release of energy occurs called as exergonic reactions.

General Characteristics of Exergonic reactions:

⇒ Reactants contains more energy than the products.

⇒ Exergonic reactions occurs spontaneously. They do not requires initial push to start.

Such type of reactions, carry on own its own.

For Example:

Flow of water from higher concentration to lower concentration.

2. Endergonic Reactions:

Such reactions, in which energy is absorbed are known as endergonic reactions.

General Characteristics of Endergonic reactions:

In endergonic reactions, products contains more energy than the reactants.

Endergonic reactions are non-spontaneous reactions.

These reactions requires initial push to start. The do not carry on own its own.

For Example:

Burning of candle.

Rate of Reaction:

The amount of reactant compound/substance converted into product compound/substance in a given period of time duration is called rate of reaction.

Factor effecting reaction rate:

  1. In exergonic reactions, rate of reaction does not depend on the how much amount of energy the reaction releases. But it depends on the amount of energy requires to start a chemical reaction.

  2. If the activation will be maximum, the reaction occurs slowly.

Catalyst and catalysis:


It is a substance that accelerates a chemical reaction , by decreasing a activation energy without being used itself.

Affecting a chemical bond in a way that lowers the activation energy of a chemical reaction is called catalysis.

The substance that cause catalysis is called as catalyst.

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