Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want preparation of salts — choosing the right method and carrying out practical steps — to become a reliable source of marks instead of a procedure-guessing exercise.
What query it owns: how to understand and revise preparation of salts in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the preparation-of-salts revision-guide angle, while Tutopiya’s Preparation Of Salts subtopic page owns the learning resource and the free Preparation Of Salts quiz owns the practice.

Salts are made by reacting acids with metals, bases or carbonates, or by combining solutions of ions. Cambridge IGCSE Coordinated Science (0654) expects you to select the correct preparation method, describe the steps, and explain why excess reactant or filtration is used. This guide maps each salt type to the method examiners expect.

Key takeaways

• Soluble salts from acids: use excess solid reactant, filter, evaporate/crystallise.
• Soluble salts from alkalis: use titration (acid + alkali) — no excess needed.
• Insoluble salts: use precipitation — mix two solutions, filter, wash, dry.
• Excess solid ensures all acid reacts; filter off unreacted solid before crystallising.
• Crystallisation produces pure solid salt from a concentrated solution.

What is preparation of salts in Cambridge IGCSE Coordinated Science?

Different salts require different routes depending on solubility and reactant availability. Acid + excess metal/metal oxide/metal carbonate gives a soluble salt after filtering excess solid. Acid + alkali needs titration because both are liquids and excess cannot be filtered. Insoluble salts form as precipitates when two solutions are mixed.

You can read the full explanation, method diagrams and notes on Tutopiya’s Preparation Of Salts subtopic page before you attempt questions.

Choosing the right method

Salt type	Reactants	Method	Key steps
Soluble (e.g. MgSO₄)	Acid + excess metal/oxide/carbonate	Excess solid method	React → filter → evaporate → crystallise
Soluble (e.g. NaCl)	Acid + alkali	Titration	Titrate → mix solutions → evaporate → crystallise
Insoluble (e.g. BaSO₄)	Two soluble salts	Precipitation	Mix → filter precipitate → wash → dry

Step-by-step — excess solid method

Step	Action	Reason
1	Add excess metal/oxide/carbonate to warm acid	Ensures all acid reacts
2	Filter	Remove unreacted excess solid
3	Evaporate filtrate partly	Concentrate the solution
4	Leave to crystallise / heat gently	Obtain pure salt crystals

Preparation of salts in past-paper wording

Command word	What the question wants	Typical stem
Describe	Practical procedure	”Describe how to prepare copper sulfate crystals.”
Explain	Why a step is needed	”Explain why excess magnesium is used.”
Name	Method for a given salt	”Name the method to prepare barium sulfate.”
State	Observation or product	”State what is filtered off after the reaction.”

Worked exam-style stems

1. “Describe how to prepare a pure, dry sample of magnesium sulfate from magnesium oxide and sulfuric acid.” Warm sulfuric acid, add excess magnesium oxide, stir until no more reacts, filter to remove excess oxide, evaporate filtrate to crystallisation point, leave to form crystals, dry with filter paper. Reward: excess + filter + crystallise + dry.
2. “Explain why titration is used to prepare sodium chloride from hydrochloric acid and sodium hydroxide.” Both reactants are solutions; excess alkali cannot be removed by filtration, so exact volumes are measured by titration. Reward: both liquids + cannot filter excess.
3. “Name the method used to prepare an insoluble salt such as lead(II) iodide.” Precipitation (mix solutions of soluble salts). Reward: precipitation or equivalent.

Test yourself with the Preparation Of Salts quiz once you can match each salt to its preparation method.

How salt preparation connects to the syllabus

Salt preparation applies acid-base reactions, solubility rules and practical skills. It links to identification of ions (testing products) and types of oxides. The Cambridge IGCSE Coordinated Science resource hub links every Acids, Bases And Salts subtopic.

Common mistakes students make

• Using excess solid method for acid + alkali (should use titration).
• Forgetting to filter before evaporating when excess solid is used.
• Evaporating to dryness instead of crystallising (loses water of crystallisation).
• Trying to make insoluble salts by evaporating a solution (use precipitation).
• Not explaining why excess reactant is added (to ensure all acid reacts).

When you need more support

If salt preparation describe questions keep costing marks, work through the Preparation Of Salts quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is salt preparation hard in Coordinated Science? Three methods cover most questions — learn when to use each and the key steps.

Why is excess solid used in salt preparation? To ensure all the acid reacts completely; the unreacted solid is then filtered off.

When is titration used? When preparing a soluble salt from an acid and an alkali, because both are solutions.

How do I revise salt preparation effectively? Learn the three methods with step sequences, practise describe questions, then take the quiz.

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