- Insoluble salts can be made by ionic precipitation (is also called double decomposition/double displacement).
- This involves mixing a solution that contains its positive ions with another solution that contains its negative ions.
Example:
Write the equation of the reaction that can be used to prepare the following salt:
- Calcium sulphate
- Lead chloride
- Copper carbonate
Answer:
a. Calcium sulphate
CaCl2 + NaSO4 → CaSO4 + 2NaCl
Ca(NO3)2 + ZnSO4 → CaSO4 + Zn(NO3)2
b. Lead chloride
Pb(NO3)2 + 2NaCl → PbCl2 + 2NaNO3
c. Copper carbonate
CuSO4 + Na2CO3 → CuCO3 + Na2SO4
CuCl2 + K2CO3 → CuCO3 + 2KCl
Cu(NO3)2 + Na2CO3 → CuCO3 + 2NaNO3