Testing for Anions

Ion CO₃2-, carbonate is found in limestone, or calcium carbonate (CaCO₃).

To test for it, you must first: Add a dilute acid to the sample. A gas is given off which when tested should prove to be carbon dioxide.

Sulphate and Sulphide

Sulphate is SO42- and Sulphide is SO32-

By adding barium chloride to the solution you are testing, a white precipitate will form. If you add hydrochloric acid, the sulphate (SO42-) WILL NOT dissolve and the sulphite (SO32-) will.

Halogen Tests

The test for halogens, or halide ions, is to add silver nitrate to a solution. Often, nitric acid is added first as well. If there are chloride, bromide or iodide ions in the solution they will react with silver to form a precipitate. The different precipitates are summarized in the table below.

The ionic equations for these reactions are:

1. 1
   Ag+ (aq) + Cl- (aq) ==>> AgCl (s)

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2. 2
   Ag+ (aq) + Br- (aq) ==>> AgBr (aq)

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3. 3
   Ag+ (aq) + I- (aq)

   ==>> AgI (aq)

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Testing for Anions. (2016). In ScienceAid. Retrieved Sep 30, 2023, from https://scienceaid.net/chemistry/applied/testanions.html

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