What ions cause hardness in water?

A macro photograph of a foamy lather from soap or detergent against a plain purple background.

Source: © Shutterstock

Investigate how different cations and anions in dissolved salts affect the formation of a lather in this experiment. Includes kit list and safety instructions.

Calcium, magnesium and iron(II) ions cause hardness in water, preventing a lather being formed with soap solution.

Make your lessons pop

Choose an account option to continue exploring our full range of articles and teaching resources

Free

Free access for everyone, everywhere. If you only need a few resources, start here.


What's included

  • One free teaching resource each month
  • Five free Education in Chemistry articles each month
  • Personalised email alerts and bookmarks