Precipitation is a chemical reaction
where a solid separates from the solution by combination
of ions. The solid formed is called a precipitate.
When two salt solutions are mixed,
new salt combinations become possible. The positive
metal ion in one salt solution combines with the negative
ion in the other and vice versa. If one of these salts
is insoluble, then it will precipitate from the solution.
The general formula for a precipitation
AB (aq) + XY (aq) -----> AY (s)
+ XB (aq)
Solubility is very important
in order to understand precipitation.