This exam focus covers Exam Focus within Making Salts for GCSE Chemistry. Revise Making Salts in Chemical Changes for GCSE Chemistry with 20 exam-style questions and 20 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 11 of 13
Practice
20 questions
Recall
20 flashcards
🎯 Exam Focus
Frequently Examined
Making salts is a required practical topic and appears in many question forms:
- Method questions: "Describe how to prepare a pure, dry sample of copper sulfate" — 6 marks, covering all steps
- Explain a step: "Why is excess copper oxide added?" — must say to ensure all acid reacts (1-2 marks)
- Choose the method: Given an acid and a base, state whether to use excess base filtration or precipitation (1-2 marks)
- Solubility rules: "Identify the precipitate formed when barium chloride is added to sodium sulfate" (2 marks)
- Ionic equation for precipitation: Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s) (HT, 2 marks)
6-mark method questions require: correct acid + base, heating the acid, adding excess base until no more dissolves, filtering to remove excess, evaporating, cooling to crystallise, and drying. Missing any step loses marks.
Quick Check: Why is excess copper oxide added when making copper sulfate from copper oxide and sulfuric acid?
Excess copper oxide ensures that ALL the sulfuric acid has reacted. If acid remained, it would contaminate the copper sulfate product. The excess copper oxide (which does not dissolve) can easily be removed by filtration.
Quick Check: Would you use the excess solid method or precipitation to make silver chloride? Explain.
Precipitation — because silver chloride is insoluble. You mix silver nitrate solution with dilute hydrochloric acid (or sodium chloride solution). The white silver chloride precipitate forms immediately and is collected by filtration. The excess solid method only works when the product is soluble.