Anion Tests

IGCSE Edexcel Chemistry
2.48 Tests for Cl-, Br-, I-, SO4 2-, CO3 2-
Key Concept: Silver nitrate and barium chloride are used to identify halides and sulfate ions; acids test for carbonates.

Section A: Halides

1. Describe the test for chloride, bromide and iodide ions. [3]
2. State the precipitate colors for AgCl, AgBr and AgI. [3]

Section B: Sulfates and Carbonates

3. Describe the test for sulfate ions and the positive result. [2]
4. Describe the test for carbonate ions and the confirmatory test for the gas produced. [3]

Total marks: 11

Mark Scheme

1. Add dilute nitric acid, then silver nitrate solution [3]
2. AgCl white, AgBr cream, AgI yellow [3]
3. Add dilute hydrochloric acid, then barium chloride; white ppt of BaSO4 [2]
4. Add dilute acid; CO2 produced; bubble through limewater turns milky [3]