How can you distinguish copper sulfate from copper carbonate?

• A. Acidify with hydrochloric acid, add barium chloride; white precipitate with sulfate but none with carbonate.
• B. Add sodium hydroxide; both form blue precipitates.
• C. Heat with acid; one dissolves, one doesn’t.
• D. Add sulfuric acid; both give the same reaction.

Answer: (A)

The test relies on how sulfate and carbonate ions behave with a barium salt after acid treatment. If copper sulfate is present, the solution contains sulfate ions, so adding barium chloride gives a white precipitate of barium sulfate, indicating sulfate. If copper carbonate is present, the carbonate reacts with the added acid (HCl) to form carbon dioxide and water, removing carbonate from the solution. Then adding barium chloride produces no precipitate because there are no carbonate ions left to form barium carbonate. So a precipitate appears with copper sulfate but not with copper carbonate.