Who this is for: Cambridge IGCSE Chemistry (0620) students who want preparation of salts — choosing the right method, applying solubility rules and describing practical steps — to become reliable marks instead of a jumble of methods they cannot match to a target salt.
What query it owns: how to understand and revise preparation of salts in Cambridge IGCSE Chemistry.
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.

Preparation of salts is a core practical topic in the Acids, Bases and Salts unit of Cambridge IGCSE Chemistry (0620). Examiners expect you to choose the correct method based on solubility, describe titration for soluble salts from alkalis, use excess reactant and filtration for insoluble salts, and explain crystallisation steps. This guide covers the syllabus methods, the solubility rules that decide your approach, and the question types that appear every year.

Key takeaways

• Soluble salts from alkalis are prepared by titration (acid + alkali → salt + water).
• Soluble salts from metals/carbonates use excess reactant, filter, then crystallise.
• Insoluble salts are prepared by precipitation — mix two solutions and filter the precipitate.
• All nitrates are soluble; all chlorides are soluble except AgCl and PbCl₂.

What is preparation of salts in Cambridge IGCSE Chemistry?

Salt preparation methods depend on whether the target salt and the reactants are soluble or insoluble. Soluble salts from alkalis require titration because both reactants and products are in solution — you must measure exact volumes. Soluble salts from metals or carbonates use excess solid reactant so all acid is used up, then filter off excess and crystallise. Insoluble salts are made by precipitation — mixing solutions of ions that form an insoluble salt, then filtering and drying the precipitate.

You can read the full explanation, worked examples and notes on Tutopiya’s Preparation of Salts subtopic page before you attempt questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Solubility rules	Which salts dissolve in water	”State whether barium sulfate is soluble.”
Titration method	Acid + alkali with indicator	”Describe how to prepare sodium chloride.”
Excess reactant method	Acid + excess metal/carbonate	”Describe how to prepare copper(II) sulfate.”
Precipitation	Mix solutions; filter insoluble salt	”Describe how to prepare lead(II) iodide.”
Crystallisation	Evaporate and cool to form crystals	”Describe how to obtain pure crystals.”

Solubility rules — the table you must know

Soluble	Insoluble (exceptions)
All nitrates	—
All Group 1 and ammonium salts	—
All chlorides	Except AgCl, PbCl₂
All sulfates	Except BaSO₄, CaSO₄, PbSO₄
Sodium, potassium, ammonium carbonates	Most other carbonates
Sodium, potassium, ammonium hydroxides	Most other hydroxides

Which method to use — decision guide

Target salt	Method	Key steps
Soluble salt from alkali (e.g. NaCl)	Titration	Titrate acid with alkali using indicator → evaporate → crystallise
Soluble salt from metal (e.g. MgSO₄)	Excess metal	Add excess Mg to acid → filter → evaporate → crystallise
Soluble salt from carbonate (e.g. CuSO₄)	Excess carbonate	Add excess CuCO₃ to acid → filter → evaporate → crystallise
Insoluble salt (e.g. BaSO₄, PbI₂)	Precipitation	Mix solutions of suitable ions → filter → wash → dry

How to describe a salt preparation — step by step

1. State the reactants (e.g. sulfuric acid + copper(II) oxide).
2. Add excess of the solid reactant to ensure all acid reacts.
3. Filter to remove unreacted solid.
4. Evaporate some water from the filtrate, then leave to crystallise (or heat gently and cool).
5. Filter/dry the crystals.

Once you have worked through a few, test yourself with the free Preparation of Salts quiz — it tells you fast whether the method selection has actually stuck.

Preparation of salts in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical salt preparation stem
Describe	Full practical method	”Describe how to prepare pure copper(II) sulfate crystals.”
Explain why	Reason for a step	”Explain why excess copper(II) oxide is used.”
State	Solubility or reagent	”State whether silver chloride is soluble.”
Name the method	Titration, precipitation etc.	”Name the method used to prepare barium sulfate.”
Write an equation	Balanced preparation reaction	”Write the equation for the preparation of magnesium sulfate.”

Worked exam-style stems (how to answer the wording)

1. “Describe how you would prepare a pure, dry sample of copper(II) sulfate crystals from copper(II) oxide and sulfuric acid.” Add excess copper(II) oxide to warm sulfuric acid and stir until no more reacts → filter to remove excess oxide → evaporate some water from the filtrate → leave to crystallise → filter and dry the crystals. Mark-scheme reward: excess oxide + filter + crystallise + dry.
2. “Explain why excess copper(II) oxide is used in the preparation of copper(II) sulfate.” Excess oxide ensures all the acid reacts so the solution contains only copper(II) sulfate (no unreacted acid). Excess solid is then filtered off. Reward: all acid reacts + filtered off.
3. “Describe how to prepare insoluble barium sulfate.” Mix solutions of barium chloride and sodium sulfate → white precipitate of BaSO₄ forms → filter → wash and dry the precipitate. Reward: correct reactants + filter precipitate.

When you can recognise the wording instantly, work the full set on the Acids, Bases and Salts topical past paper questions and the Preparation of Salts quiz to lock the methods in.

How salt preparation connects to the rest of the syllabus

Salt preparation links to Characteristic Properties of Acids and Bases (acid reactions) and Oxides (basic oxides as reactants). Titration also appears in quantitative analysis. When you are ready to mix topics, the Cambridge IGCSE Chemistry resource hub links every Acids, Bases and Salts subtopic.

Common mistakes students make

• Using titration when the salt is insoluble (use precipitation instead).
• Forgetting to filter off excess solid reactant before crystallising.
• Not stating excess reactant — without it, acid may remain in the product.
• Confusing evaporation to dryness with crystallisation (crystallisation gives larger, purer crystals).
• Mixing wrong ion pairs for precipitation (e.g. using soluble chlorides when AgCl is needed from AgNO₃ + NaCl).

When you need more support

If salt preparation questions keep costing marks — especially choosing the correct method — work through the Acids, Bases and Salts topical past paper questions and the Preparation of Salts quiz, then get focused help from a Cambridge IGCSE Chemistry tutor.

Frequently asked questions

Is preparation of salts hard in Cambridge IGCSE Chemistry? The methods are fixed once you know solubility rules. Marks are lost when students pick the wrong method or skip filtration/crystallisation steps.

When do I use titration instead of excess reactant? Use titration when preparing a soluble salt from an alkali (both reactants are solutions). Use excess reactant for soluble salts from metals, carbonates or oxides.

How do I prepare an insoluble salt? Mix solutions containing the required ions so a precipitate forms, then filter, wash and dry.

How do I revise salt preparation effectively? Learn solubility rules, practise describing each method in full, then take the Preparation of Salts quiz.

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