Answer:
Na2CO3 + CaCl2 → CaCO3 + 2 NaCl
Step-by-step explanation:
A double displacement reaction is a type of metathesis reaction in which two reactants exchange ions to form two new compounds. Double displacement reactions usually involve reacting two soluble salts in aqueous solution resulting in the formation of two products: a soluble salt and an insoluble salt that is produced as a precipitate.
If the reaction of two soluble compounds does not produce a precipitate, the reaction does not result in the formation of a product as basically, all the ions are mixed together in the reaction vessel.
From the given reactions above:
1. 3 KBr + AlPO4 → K3PO4 + AlBr3
The reaction does not proceed to product formation as the two products are all soluble salts.
2. Na2CO3 + CaCl2 → CaCO3 + 2 NaCl
The reaction occurs as one of the products, CaCO3 is insoluble as is produced as a precipitate.
3. NH4OH + KCl → KOH + NH4Cl
The reaction does nott occuras the products are all soluble in water.
4. ZnCl2 + Mg2SO4 → ZnSO4 + MgCl2
The reaction does not occur as the products are all soluble in water.