12 Questions
What distinguishes the Group 1 Anions from other groups?
Their calcium salts are insoluble in neutral or slightly basic solutions
What is indicated when effervescence is observed in the test described?
A chemical change taking place
Which ion is confirmed to be present when a brown color is produced after addition of Kl?
Arsenite ion
What does the formation of a yellow precipitate after adding ammonium molybdate confirm?
Presence of Phosphate ion
What indicates the presence of Oxalate ion in the test mentioned?
Disappearance of a pink color
What is confirmed when no yellow precipitate is formed in the second portion involving the Centrifugate?
Absence of Arsenite ion
What is the purpose of adding KCIO₂ in an acid solution in procedure #1?
To oxidize sulfate, sulfide and thiosulfate ions
Why is a confirmatory test important in the qualitative analysis of Group 1 Anions?
To identify individual ions present in the unknown
What is the purpose of thoroughly washing the residue in this test?
To remove any interfering ions
Which reagent is used to confirm the presence of arsenite ion?
Thioacetamide
What compound is formed when fluoride ion reacts with CC₁₁₂?
Silicon tetrafluoride
Why is it necessary to oxidize sulfate, sulfide, and thiosulfate ions in procedure #1?
To free sulfur or sulfate ions for identification
Study Notes
Group 1 Anions
- The Group 1 Anions consist of Carbonate (CO2-), Sulfite (SO32-), Oxalate (C₂O2-), Fluoride (F-), Arsenite (ASO3-), Arsenate (AsO3-), and Phosphate (PO4³-).
Characteristics of Group 1 Anions
- The calcium salts of these anions are insoluble in neutral or slightly basic solution.
Effervescence
- Effervescence is the release of a gas from a solid or liquid, forming bubbles in a liquid medium, indicating a chemical change.
- In the context of Group 1 Anions, effervescence refers to the release of carbon dioxide gas.
Identification of Group 1 Anions
- Sulfite ion (SO32-): forms a white precipitate with Barium sulfate (BaSO4).
- Arsenite ion (ASO3-): forms a yellow precipitate with Arsenic trisulfide (As₂S₃).
- Phosphate ion (PO4³-): forms a yellow precipitate with Ammonium phosphomolybdate ((NH4)3PO4.12MoO3).
- Oxalate ion (C₂O2-): presence confirmed by the disappearance of a pink color with Manganese ion (Mn²+).
- Fluoride ion (F-): presence confirmed by the etching of glass with Silicon tetrafluoride (SiF₄).
Importance of Confirmatory Tests
- Confirmatory tests are essential to identify individual ions present in a given unknown sample.
Test your knowledge about the Group 1 Anions - Carbonate, Sulfite, Oxalate, Fluoride, Arsenite, Arsenate, and Phosphate. Learn about their properties and how to differentiate them from other anion groups.
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