Qualitative Analysis: A Level Chemistry OCR | Questions and Answers with complete solution
Test for carbonates - Add dilute Nitric Acid - see bubbling: May be a carbonate Bubbles - carbon dioxide To prove it is carbon dioxide, bubble through limewater - should turn from clear to cloudy Na₂CO₃(aq) + 2HNO₃(aq) → 2NaNO₃(aq) + CO₂(g) + H₂O(l) Testing for sulphates - Add Barium Ions (Barium Chloride/Nitrate) White Precipitate seen - Barium Sulphate Ba²⁺(aq) + SO₄²⁻ → BaSO₄(s) Halide Testing - Add AgNO₃ (Silver Nitrate) Silver Halide precipitate seen - means halide ions were present AgCl - White AgBr - Cream AgI - Yellow (Gets darker down the group) Further Halide Testing - Add dilute NH₃(aq) then conc. NH₃(aq)Colours can be difficult to tell apart AgCl - Precip dissolves in dilute AgBr- Precip dissolves only in conc. AgI - Precip does not dissolve Sequence of Testing - Carbonate ions → Sulphate ions → Halide ions Why? Neither SO₄²⁻ or X⁻ produce carbon dioxide gas Barium Carbonate also insoluble Silver Carbonate and Silver Sulphate both insoluble Testing a Mixture of ions - Test on the same solution
Document information
- Uploaded on
- July 11, 2023
- Number of pages
- 3
- Written in
- 2022/2023
- Type
- Exam (elaborations)
- Contains
- Questions & answers
