How can you distinguish hydrochloric acid from nitric acid using a silver nitrate test?

• A. Silver nitrate forms a white precipitate with hydrochloric acid but not with nitric acid.
• B. Litmus paper turns blue for hydrochloric acid and red for nitric acid.
• C. Barium chloride produces a white precipitate with nitric acid but not with hydrochloric acid.
• D. Heating the acids causes different gases to evolve.

Answer: (A)

The test relies on the chloride ion detectability with silver ions. Silver ions react with chloride ions in solution to form silver chloride, which is an insoluble white precipitate. Hydrochloric acid supplies chloride ions, so when you add silver nitrate you get a white precipitate, indicating chloride is present. Nitric acid does not contain chloride ions, only nitrate ions, so there’s no AgCl precipitate formed. That difference lets you tell the acids apart using this silver nitrate test. Other quick checks, like litmus, won’t distinguish them because both acids turn red, since both are strong acids.