Higher Tier: Additional Ion Tests
Part of Tests for Ions — GCSE Chemistry
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 topic appears regularly enough that it should still be part of a steady revision cycle. It is section 11 of 14 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 11 of 14
Practice
20 questions
Recall
14 flashcards
🎓 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)
Distinguishing Fe²⁺ from Fe³⁺ More Precisely
Potassium thiocyanate (KSCN) provides a more sensitive test: Fe³⁺ + SCN⁻ → blood-red solution. Fe²⁺ does not give this blood-red colour.
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)