A qualitative test for sulfate ions (SO42−\text{SO}_4^{2-}SO42−) in an aqueous solution involves adding a few drops of dilute hydrochloric acid followed by aqueous barium chloride (BaCl2\text{BaCl}_2BaCl2) solution.
What is the reason for adding the dilute hydrochloric acid?
To convert BaCl2\text{BaCl}_2BaCl2 into [BaCl4]2−[\text{BaCl}_4]^{2-}[BaCl4]2−
To decrease the solubility of barium sulfate
To increase the pH of the solution
To prevent the precipitation of other insoluble barium compounds
