Answer:
For the first reaction the reagents are: MgCl2 and Na2CO3
For the second reaction the reagents are: Na2HPO4 and CaCl2
Explanation:
Precipitation reactions lie in the production of a compound that is not soluble, which is called a precipitate, this precipitate is produced when two different solutions are combined, each of which will contribute an ion for the formation of the precipitate. In the first reaction you have:
MgCl2 + Na2CO3 = MgCO3 + 2 NaCl
Type of reaction: double displacement
The second reaction is as follows:
4Na2HPO4 + 3CaCl2 → Ca3 (PO4) 2 + 2NaH2PO4 + 6NaCl
It is the reaction of sodium hydrochlorophosphate and calcium chloride