Reversible Reactions

Reversible reactions are ones which occur in both directions at the same time.

We represent them using a double arrow: reactants 

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If a reversible reaction is exothermic (gives out energy) in one direction it is endothermic (takes in energy) in the other direction.

When a reversible reaction takes place in a closed system an equilibrium will be reached. This means that the forward and the backward reactions occur at the same rates.

In a closed system if the conditions are changed then the position of the equilibrium will move to minimise the effect of the change in conditions.

- N_2(g) + 3H_2(g) 

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2NH_3(g) this reaction is exothermic: increasing the temperature will move the equilibrium in favour of the reactants, in the endothermic direction. The system ‘tries’ to take in the extra energy.

These factors, together with reaction rates, are important when determining the optimum conditions in industrial processes

This video shows an Exothermic reaction

Whilst this video shows an Endothermic reaction