Solubility:Solubility refers to how much of a substance can dissolve in a given solvent at a certain temperature. In this case, we want to decrease the solubility of lithium carbonate by adding another compound.
Precipitate:A precipitate is an insoluble solid that forms when two solutions react with each other. In our case, we want to increase the precipitation of lithium carbonate by adding another compound.
Common Ion Effect:The common ion effect occurs when the presence of an ion already present in solution reduces the solubility of another compound containing that same ion. Adding a compound with common ions will help increase the precipitation of lithium carbonate.