Tests for negative ions (anions)

Question 1

What’s the test and result for

Carbonate (CO₃²⁻)

Answer 1

Test: Add dilute hydrochloric acid to solid

Result: Effervescence (fizzing), carbon dioxide produced (test with limewater)

Question 2

What’s the test and result for

Chloride (Cl⁻) (in solution)

Answer 2

Test: Acidify solution with dilute nitric acid, then add aqueous silver nitrate

Result: White precipitate of silver chloride formed; precipitate soluble in ammonia solution

Question 3

What’s the test and result for

Sulfate (SO₄²⁻) (in solution)

Answer 3

Test: Acidify solution with dilute nitric acid, then add barium nitrate solution

Result: White precipitate of barium sulfate formed

Question 4

What’s the test and result for

Nitrate (NO₃⁻) (in solution)

Answer 4

Test: Make solution alkaline with sodium hydroxide solution, then add aluminium foil and warm carefully

Result: Ammonia gas given off (test with moist red litmus)