This higher tier covers Higher Tier: Additional Ion Tests within Tests for Ions for GCSE Chemistry. Revise Tests for Ions in Chemical Analysis for GCSE Chemistry with 20 exam-style questions and 14 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 15 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.

🎓 Higher Tier: Additional Ion Tests

Ammonium Ion (NH₄⁺)

Test: Add sodium hydroxide solution and warm gently.

Positive result: Ammonia gas evolved — turns damp red litmus paper blue.

Equation: NH₄⁺(aq) + OH⁻(aq) → NH₃(g) + H₂O(l)

Solubility Rules (useful context)

All nitrates are soluble
All Group 1 compounds are soluble
Most sulfates are soluble (except BaSO₄, PbSO₄, CaSO₄ slightly)
Most carbonates are insoluble (except Group 1)

Practice questions for Tests for Ions

Which reagents are used to test for carbonate ions in a solution?

A. Add barium chloride solution, then dilute HCl
B. Add dilute acid, then test the gas with limewater
C. Add silver nitrate solution, then dilute HNO3
D. Add sodium hydroxide solution and warm

1 markfoundation

Describe how sodium hydroxide solution can be used to distinguish between iron(II) ions and iron(III) ions in solution, including the expected observations.

3 marksstandard

Quick recall flashcards

What is a precipitation reaction?

A reaction where two soluble ionic compounds react to form an insoluble precipitate. General form: A⁺(aq) + B⁻(aq) → AB(s)

How do you test for sulfate ions (SO₄²⁻)?

Add barium chloride solution + dilute HCl. White precipitate of BaSO₄ forms. Equation: Ba²⁺ + SO₄²⁻ → BaSO₄(s)

Higher Tier: Additional Ion Tests