Chlorine (Oxford AQA IGCSE Chemistry)

Revision Note

Alexandra Brennan

Expertise

Chemistry

Test for Chlorine Gas

  • The test for chlorine makes use of litmus paper

  • If chlorine gas is present, damp blue litmus paper will turn red and then be bleached white

  • It turns red initially as acids are produced when chlorine comes into contact with water

  • Chlorine also has a characteristic sharp, choking smell 

  • Chlorine should always be handled in a fume cupboard due to its toxicity

Testing for chlorine gas

The diagram shows damp blue litmus paper being placed into chlorine gas and then turning red before bleaching to a final white colour
Chlorine bleaches damp blue litmus paper white

Exam Tip

You should distinguish between properties of gases and tests for gases. Chlorine 'smells like swimming pools' is a characteristic, but it is not an acceptable means of identification. 

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Alexandra Brennan

Author: Alexandra Brennan

Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.