How to Test for Hydrogen Chloride?
Hydrogen chloride is a toxic corrosive gas with the chemical formula HCl. This gas readily dissolves in water to form hydrochloric acid. Hydrochloric acid is a common laboratory reagent and it is also used in industry. This acid is a major component of gastric juice. Determining the presence of the compound is a usual chemistry lab task. You need two tests to identify hydrogen chloride. The first one measures the acidity of the solution. The second test uses a silver nitrate (AgNO3) solution to determine the presence of chloride ions.
Instructions In Solution:
1.Pour about 2 to 3 milliliters of the solution to be tested into the beaker.
2.Tear off a piece of the pH paper.
3.Dip one end of the pH paper strip into the solution and quickly remove it. The part of the litmus paper that was in contact with the solution will change color.
4.Compare the color of the paper with the color scale of the packet of the pH paper to determine the acidity of the solution. A pH below 2 is indicative for hydrogen chloride, and means the solution is strongly acidic.5.Fill a pipette with the silver nitrate solution.6.Add three to five drops from the pipette to the beaker.
7.Observe the solution in the beaker: If a thick, white precipitate forms, it is indicative for hydrogen chloride. Note that this test reaction follows the equation HCl + AgNO3 = AgCl (precipitate) + HNO3.
Test for Hydrogen Chloride Gas 8.Tear off a piece of the pH paper.9.Moisturize one end of the pH paper strip with distilled water.
10.Place the moisturized end of the pH paper strip into the test tube with the gas. Then take it out immediately.
11.Compare the color of the paper with the color scale of the packet of the pH paper to determine the acidity of the gas. A pH below 2 is indicative for hydrogen chloride. If the gas is only slightly acidic (a pH of about 5), then it might be carbon dioxide gas rather than hydrogen chloride.
