Question

What reagent could be used to separate Br- from SO₄²⁻ when added to an aqueous solution containing both?

1) AgNO₃
2) NaCl
3) HCl
4) NaOH

Answer 1

The reagent used to separate Br- from SO4^2- in an aqueous solution is AgNO3, as it precipitates Br- as insoluble AgBr, leaving SO4^2- in solution.

Step-by-step explanation:

To separate Br-from SO42- in an aqueous solution, one could add a reagent that would precipitate one of the ions without affecting the other. Among the given options, AgNO3 (silver nitrate) is the correct choice. When AgNO3 is added to the solution, it will react with Br- to form a cream-colored precipitate of AgBr (silver bromide), which is insoluble in water.

The net ionic equation for this reaction would be Ag+(aq) + Br-(aq) → AgBr(s). Meanwhile, the sulfate ion, SO42-, does not react with AgNO3 under these conditions because Ag2SO4 is moderately soluble in water.