Question

The mixing of which pair of reactants will result in a precipitation reaction?

Answer 1

NH4Br and NH4I are both soluble in water, and they don't react with each other. So this pair will not form precipitation.

NaClO4 and (NH4)2S are both soluble in water. While in water, they dissociate into Na+, ClO4-, NH4+ and S2- ions, which don't react with each other. So this pair will not form precipitation.

Ni(NO3)2 and Na2CO3 are both soluble in water. When the 2 solutions combine, NiCO3 forms. NiCO3 is not soluble in water, so it will precipitate out from the solution. This pair will result in precipitation.

K2SO4 and Cu(NO3)2 are both soluble in water. While in water, they dissociate into K+, SO42-, Cu2+ and NO3- ions, which don't react with each other. So this pair will not form precipitation.

Step-by-step explanation:

Hope this helps...