List the observations of the following anion tests: Br-, I-, CO32-, HCO3-, NO3-, NO2-, SO42-, and CH3COO-.

Here are the observations for the anion tests:

• Br⁻

  • Reagent: HNO₃/AgNO₃(aq) then Conc NH₃
  • Observation: Cream precipitate formed. Precipitate is soluble in concentrated NH₃.

• I⁻

  • Reagent: HNO₃/AgNO₃(aq) then Conc NH₃
  • Observation: Yellow precipitate formed. Precipitate is insoluble in concentrated NH₃.

• CO₃²⁻

  • Reagent: MgSO₄(aq) at r.t.p.
  • Observation: White precipitate formed.

• HCO₃⁻

  • Reagent: MgSO₄(aq) + boiling
  • Observation: No precipitate formed at r.t.p. White precipitate formed on boiling.

• NO₃⁻

  • Reagent: FeSO₄(aq) + conc. H₂SO₄, no shaking
  • Observation: A brown ring formed at the junction of the two layers.

• NO₂⁻

  • Reagent: FeSO₄(aq) + conc. H₂SO₄, no shaking
  • Observation: Brown solution or brown ring formed.

• SO₄²⁻

  • Reagent: Pb(CH₃COO)₂(aq), Heat then cool.
  • Observation: White precipitate formed. Precipitate dissolves on heating and reappears on cooling.

• I⁻

  • Reagent: Pb(CH₃COO)₂(aq), Heat then cool.
  • Observation: Yellow precipitate formed. Precipitate dissolves on heating to form a colorless solution and reappears as golden-yellow flakes on cooling.

• CH₃COO⁻

  • Reagent: FeCl₃(aq) at r.t.p
  • Observation: Blood-red coloration formed.

• S₂O₃²⁻

  • Reagent: FeCl₃(aq) at r.t.p
  • Observation: Transient violet coloration formed, which quickly fades.

• CrO₄²⁻

  • Reagent: AgNO₃(aq) + NH₃(aq) then dil HNO₃
  • Observation: Reddish-brown precipitate formed. Precipitate dissolves in NH₃(aq) and reappears upon addition of dil HNO₃.

• Cr₂O₇²⁻

  • Reagent: Dil. SnCl₂(aq)
  • Observation: Orange solution turns green.