Reversible Reactions and Dynamic Equilibria

Reversible Reactions and Dynamic Equilibria

Some reactions are reversible. Reversible reactions are indicated by the symbol

Some examples of reversible reactions include:

• Copper (II) Sulphate Crystals

Heating the blue hydrated copper (II) sulphate crystals causes them to lose their water of crystallisation, making them turn from blue to white – the white copper (II) sulphate crystals are described as ‘anhydrous’ meaning ‘without water’:

CuSO₄•5H₂O -> CuSO₄ + 5H₂O

However, this reaction can be reversed by simply adding water to the crystals. The crystals will become hydrated again:

CuSO₄ + 5H₂O -> CuSO₄•5H₂O

• Heating Ammonium Chloride

When ammonium chloride is heated in a test tube, the white crystals decompose into hydrogen chloride gas and ammonia gas. These flow upwards and recombine again further up the test tube:

NH₄Cl -> HCl + NH₃

This later recombines:

HCl + NH₃ -> NH₄Cl