# Reversible Reaction

Show/Hide Sub-topics (Chemical Reactions | O Level)

A reversible reaction ($\rightleftharpoons$) is a reaction that can take place in both directions – i.e. forward reaction and backward reaction.

When the rate of forward reaction is equal to the rate of backward reaction, the reaction is said to have reached a state of dynamic equilibrium.

When a chemical reaction reaches a state of dynamic equilibrium:

• the rate of forward reaction is equal to the rate of backward reaction
• the concentration of reactants and products remain unchanged (constant)

The composition of an equilibrium mixture in a reversible reaction can be altered by changes in:

• concentration
• temperature
• pressure

## Le Chatelier’s Principle

Le Chatelier’s Principle is used to predict the change in composition of an equilibrium mixture. Le Chatelier’s Principle states that:

If the conditions of a system in dynamic equilibrium are altered, the system will move so as to oppose the change.

## Changing Concentration

The table below shows the effect of changing concentration (conc.) for a reversible reaction

## Changing Temperature

The table below shows the effect of changing temperature (temp.) for a reversible reaction

## Changing Pressure

The table below shows the effect of changing pressure for a reversible reaction