Question

BaCl 2 would also have precipitated some other ions in addition to the sulfate ion had they been present in the sample. For example, if carbonate ion, CO3 2– , had been present in the sample, it would also have been precipitated by barium chloride

Ba 2+ (aq) + CO3 2– (aq) → BaCO3(s)

How was the precipitation of carbonate ion avoided?

Answer 1

precipitation of carbonate ion avoided If we add acid (H+) and heat to the solution.

when acid (H+) added to solution then H+ react with carbonate ion to form H2CO3 which decompose to form CO2 and H2O.

2 H+ (aq) + CO₃^2- (aq)............> H2CO3 (aq)

H2CO3 (aq)...................> CO2 (g) + H2O (l)

CO2 gas remove away from solution.

thus we can avoid the precipitation of carbonate ion.