Tests for Water (Edexcel IGCSE Chemistry: Double Science)

Revision Note

Test yourself
Stewart

Author

Stewart

Last updated

Test for water

  • Water can be identified using a chemical test and/or a physical test

Chemical test for water

  • Anhydrous copper(II) sulfate turns from white to blue on the addition of water
  • The equation is:

CuSO4 (s) + 5H2O (l) → CuSO4.5H2O (s)

Copper sulfate turns a light blue colour in the presence of water

Physical test for water

  • A physical test to see if a sample of water is pure is to check its boiling point
  • A sample of the liquid is placed in a suitable container such as a boiling tube and gently heated
  • Using a thermometer, you can check if the boiling point is exactly 100 oC
  • Any impurities present will usually tend to raise the boiling point and depress the melting point of pure substance

Examiner Tip

A lot of students are tempted to say you can identify water because it has no taste or smell. While this may be true, it would be extremely hazardous to taste anything in the lab and water is not the only colourless liquid to have no taste or smell!

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Stewart

Author: Stewart

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Exam Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.