Preparation of salts — KCSE Chemistry

KCSE Chemistry · 60 practice questions · 4 syllabus objectives

24 easy24 medium12 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Describe the preparation of soluble salts by neutralisation, reaction of acid with metal and reaction of acid with carbonate

Describe the preparation of insoluble salts by precipitation (double decomposition)

Write ionic equations for salt preparation reactions and select the appropriate method for a given salt

Preparation of salts

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easySHORT ANSWER4 marks

Define the term 'precipitation reaction' and give one example of how to prepare an insoluble salt. (4 marks)

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Part (a) — 2 marks

A precipitation reaction is a chemical reaction in which two soluble salts react to form an insoluble salt (precipitate). (1 mk)

The insoluble salt usually appears as a solid that settles out of the solution. (1 mk)

Part (b) — 2 marks

An example is the preparation of barium sulfate by mixing barium chloride with sodium sulfate. (1 mk)

The reactants used are barium chloride (BaCl2) and sodium sulfate (Na2SO4). (1 mk)

easySHORT ANSWER4 marks

Explain how you would prepare silver chloride using the precipitation method. (4 marks)

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Part (a) — 2 marks

Mix a solution of silver nitrate with a solution of sodium chloride. (1 mk)

Stir the mixture to ensure complete reaction leading to the formation of the white precipitate of silver chloride. (1 mk)

Part (b) — 2 marks

To separate the insoluble silver chloride precipitate from the soluble sodium nitrate solution. (1 mk)

Filtering ensures that only the desired product (silver chloride) is collected for further use. (1 mk)

easySHORT ANSWER4 marks

Identify two properties of the salt formed when hydrochloric acid reacts with sodium hydroxide. (4 marks)

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Part (a) — 4 marks

The salt is soluble in water (1 mk)

The salt has a neutral pH when dissolved in water (1 mk)

The salt forms a colourless solution (1 mk)

The salt can be crystallised from its solution (1 mk)

Identify the method used to prepare copper(II) sulfate from copper(II) oxide and sulfuric acid. (2 marks)