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Learning objective

Describe the methods to identify the following gases: (a) ammonia (NH₃) using damp red litmus paper, (b) carbon dioxide (CO₂) using limewater, (c) chlorine (Cl₂) using damp litmus paper, (d) hydrogen (H₂) using a lighted splint, and (e) oxygen (O₂) using a glowing splint.

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Cambridge IGCSE Combined ScienceExperimental techniques and chemical analysisCore content

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Describe the methods to identify the following gases: (a) ammonia (NH₃) using damp red litmus paper, (b) carbon dioxide (CO₂) using limewater, (c) chlorine (Cl₂) using damp litmus paper, (d) hydrogen (H₂) using a lighted splint, and (e) oxygen (O₂) using a glowing splint

  • This point belongs to Identification of ions and gases, especially Identification of ions and gases outcomes.
  • You need to be able to describe the methods to identify the following gases: (a) ammonia (NH₃) using damp red litmus paper, (b) carbon dioxide (CO₂) using limewater, (c) chlorine (Cl₂) using damp litmus paper, (d) hydrogen (H₂) using a lighted splint, and (e) oxygen (O₂) using a glowing splint.
  • The key ideas to know are Describe, Identify, and Explain.
  • Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

DescribeIdentifyExplain

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Paper 3 structured question: Identification of ions and gases

Paper 3Theory (Core)2 marks

Description

Gas Identification Tests

You are provided with several gases: ammonia, carbon dioxide, chlorine, hydrogen, and oxygen. Describe how you would identify each gas using appropriate tests.

  1. a

    Describe the method to identify ammonia using damp red litmus paper.

    Aim for approximately 2 distinct marking points.

    [2]
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