Precipitation (chemistry) - Representation Using Chemical Equations

Representation Using Chemical Equations

An example of a precipitation reaction: Aqueous silver nitrate (AgNO₃) is added to a solution containing potassium chloride (KCl), the precipitation of a white solid, silver chloride is observed. (Zumdahl, 2005)

AgNO₃ (aq) + KCl (aq) → AgCl (s) + KNO₃ (aq)

The silver chloride (AgCl) has formed a solid, which is observed as a precipitate.

This reaction can be written emphasizing the dissociated ions in a combined solution. This is known as the ionic equation.

Ag+ (aq) + NO₃− (aq) + K+ (aq) + Cl− (aq) → AgCl (s) + K+ (aq) + NO₃− (aq)

A final way to represent a precipitate reaction is known as a net ionic reaction. In this case, any spectator ions (those that do not contribute to the reaction) are left out of the formula completely. This simplifies the above equations to the following:

Ag+ (aq) + Cl− (aq) → AgCl (s)