Question

Based on this, which of the reactions below

are double-replacement reactions?
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
2 AgNO3(aq) + Zn(8) + 2Ag(s) + Zn(NO3)2(aq)
Pb(NO3)2(aq) + 2KI(aq) + 2KNO3(aq) + Pb12(s)
BaCl2(aq) + Na2SO4 (aq) + BaSO4(s) + 2NaCl(aq)

Answer 1

BaCl2(aq) + Na2SO4 (aq) → BaSO4(s) + 2NaCl(aq)

Step-by-step explanation:

Chemical reactions are of different types namely; combination reaction, displacement reaction, double displacement reaction etc. Double displacement/replacement reaction is that reaction in which an exchange of ions occur between two reacting ionic compounds to form new products.

In this chemical reaction/equation;

BaCl2(aq) + Na2SO4 (aq) → BaSO4(s) + 2NaCl(aq)

2Cl- and SO42- are the ions exchanged in this reaction. Barium (Ba) displaces SO42-, while Sodium (Na) displaces 2Cl-, hence it is called DOUBLE DISPLACEMENT OR REPLACEMENT because the displacement involves two compounds/ions.