Examples of reversible reactions
Ammonium chloride
Ammonium chloride is a white solid. It breaks down when heated, forming ammonia and hydrogen chloride. When these two gases are cool enough, they react together to form ammonium chloride again. This A chemical reaction which can go both ways, so that products can turn back into reactants. can be modelled as:
ammonium chloride ⇌ ammonia + hydrogen chloride
NH4Cl(s) ⇌ NH3(g) + HCl(g)
The symbol ⇌ has two half arrowheads, one pointing in each direction. It is used in equations that are reversible reactions:
- the forward reaction is the one that goes to the right
- the backward reaction is the one that goes to the left
Copper(II) sulfate
Blue copper(II) sulfate is described as Means that the solid crystals contain water of crystallisation.. The copper(II) ions in its crystal lattice structure are surrounded by water molecules. This water is driven off when blue hydrated copper(II) sulfate is heated, leaving white A substance containing no water. copper(II) sulfate. This reaction is reversible:
hydrated copper(II) sulfate ⇌ anhydrous copper(II) sulfate + water
CuSO4.5H2O(s) ⇌ CuSO4(s) + 5H2O(l)
Image caption, 1. A Bunsen burner is used to heat an evaporating basin containing hydrated copper(II) sulfate.
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