Tests for Anions

chloride test

add a few drops of AgNO₃ solution to a solution of the solid

chloride observations

a white precipitate is formed which is soluble in dilute ammonia solution

chloride inference

Ag⁺ + Cl^- = AgCl/

Sulfate/sulfite test

1. add BaCl₂ solution to a solution of the solid

2. distinguishing test- add dilute HCl

sulfate/sulfite observations

1. a white precipitate is formed

2. if precipitate remains after HCl - sulfate

3. if precipitate dissolves - sulfite

sulfate/sulfite inference

1.Ba²⁺ + SO₄ ^2- = BaSO₄ /

Ba²⁺ + SO₃ ^2- = BaSO₃ /

2. BaSO₄ + HCL = no reaction

3. SO₃ ^2- +2H⁺ = SO₂ + H₂O

Carbonate/Hydrogen-carbonate test

1. add dilute HCl to the solid

2. Distinguishing test. add MgSO₄ to a fresh solution of the solid

Carbonate/Hydrogen-carbonate

1.Fizzing. A gas forms that turns limewater milky.

• Distinguishing test. If white precipitate forms - carbonate

• no precipitate forms - hydrocarbonate 

boiling gives a precipitate

carbonate/hydrogen-carbonate inference

1.CO₃ ^2- +2H⁺ = CO₂ +H₂O

HCO₃ ^- +H⁺ = CO₂ + H₂O

Ca(OH)₂ + CO₂ = CaCO₃ / + H₂O

2.Mg²⁺ + CO₃ ^2- = MgCO₃ /

3.Mg²⁺ + 2HCO₃ ^- =MgCO₃ /

Mg(HCO₃ )₂ = MgCO₃ / +CO₂ + H₂O

Nitrate test

Brown ring test. To a solution of the solid add freshly prepared FeSO₄ solution. Add concentrated sulfuric acid.

Nitrate observations

a brown ring is formed at the junction of the two liquids - nitrate ion present

nitrate inference

brown ring is due to presence of nitrate ion

phosphate test

ammonium molybdate is added to a solution of the solid. concentrated nitric acid is added. solution is warmed

phosphate observations

yellow precipitate is formed

phosphate inference

yellow precipitate shows phosphate ions are present