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Learning objective

Outline the tests using aqueous sodium hydroxide and aqueous ammonia to identify the following cations: (a) ammonium (NH₄⁺), (b) calcium (Ca²⁺), (c) copper(II) (Cu²⁺), (d) iron(III) (Fe³⁺), (e) iron(II) (Fe²⁺), and (f) zinc (Zn²⁺). Note that the formulas of complex ions are not necessary.

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Cambridge IGCSE Combined ScienceExperimental techniques and chemical analysisCore content

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Outline the tests using aqueous sodium hydroxide and aqueous ammonia to identify the following cations: (a) ammonium (NH₄⁺), (b) calcium (Ca²⁺), (c) copper(II) (Cu²⁺), (d) iron(III) (Fe³⁺), (e) iron(II) (Fe²⁺), and (f) zinc (Zn²⁺). Note that the formulas of complex ions are not necessary

  • This point belongs to Identification of ions and gases, especially Identification of ions and gases outcomes.
  • You need to be able to outline the tests using aqueous sodium hydroxide and aqueous ammonia to identify the following cations: (a) ammonium (NH₄⁺), (b) calcium (Ca²⁺), (c) copper(II) (Cu²⁺), (d) iron(III) (Fe³⁺), (e) iron(II) (Fe²⁺), and (f) zinc (Zn²⁺). Note that the formulas of complex ions are not necessary.
  • The key ideas to know are Describe, Outline, and Identify.
  • Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

DescribeOutlineIdentify

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Paper 3 structured question: Identification of ions and gases

Paper 3Theory (Core)2 marks

Description

Cation Identification Tests

You are provided with solutions containing various cations. You need to identify the cations using sodium hydroxide and ammonia.

  1. a

    Outline the test for identifying iron(II) ions using sodium hydroxide.

    Aim for approximately 2 distinct marking points.

    [2]
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