8.3.5

Halides, Sulfates

Test yourself

Testing for Halides

Halide ions are negatively charged (they are anions). There are 2 steps to halide testing:

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Add dilute nitric acid

  • Add dilute nitric acid to an unknown solution.
    • This removes carbonate ions. These could disrupt test results by forming a precipitate with the silver ions added in step 2.
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Add silver nitrate

  • Add silver nitrate to the same solution.
    • If halide ions are present, they will form a precipitate with the silver ions:
      • Ag+(aq) + Cl-(aq) → AgCl(s) (silver chloride is white).
      • Ag+(aq) + Br-(aq) → AgBr(s) (silver bromide is cream).
      • Ag+(aq) + I-(aq) → AgI(s) (silver iodide is pale yellow).

Testing for Sulfates

Sulfates are compounds that contain SO42- ions. There are 2 steps to sulfate testing:

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Add dilute hydrochloric acid

  • Add dilute hydrochloric acid to an unknown solution.
    • This removes carbonate ions. These could disrupt test results by forming a precipitate with the barium ions added in step 2.
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Add barium chloride

  • Add barium chloride to the same solution.
    • If sulfates are present, the white precipitate barium sulfate will form:
      • Ba2+(aq) + SO42-(aq) → BaSO4(s)

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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