Back to Separate Sciences (Biology, Chemistry, Physics)Practice this
Paper 2
Chemical Analysis
Both
Rf = distance moved by spot ÷ distance moved by solvent.
Key Facts
- Flame tests: Na yellow, K lilac, Cu green.
- Pure substances have fixed melting and boiling points.
Topics Covered
Gas Tests
What you need to know
- •Hydrogen: squeaky pop.
- •Oxygen: relights a glowing splint.
Exam Tips
- Always state the test and the result.
Ion Tests
What you need to know
- •Carbonates release CO2 with acid.
- •Halide ions form precipitates with silver nitrate.
Exam Tips
- Use colors: AgCl white, AgBr cream, AgI yellow.
Chromatography
What you need to know
- •Separates mixtures based on solubility.
- •Rf = distance moved by substance / distance moved by solvent.
Exam Tips
- Use pencil for the start line.
Key Terms
Precipitate
An insoluble solid formed in a reaction.
Chromatography
Technique for separating mixtures.
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Common Exam Questions
Describe the test for chloride ions.
3 marksmediumPaper 2
Model Answer
Add dilute nitric acid then silver nitrate; a white precipitate forms.
What examiners want to see
- ✓Use nitric acid first.
- ✓State white precipitate.
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