MYP 8 Science - Chemistry

MYP 8.6.7: Reacting bleach with acid to produce chlorine


  • To make chlorine gas in the laboratory
  • To test the gas using damp indicator paper
  • To test the gas with potassium iodide/starch indicator
  • To understand that chlorine is poisonous
  • To handle a poisonous gas safely


Bleach is a common household substance with antibacterial action due to the ease with which it releases chlorine. The correct chemical name for bleach is sodium chlorate(I). An older name, although still in use, is sodium hypochlorite.

  1. A small spatula of bleach is placed in a dry test tube and 5cm3 of hydrochloric acid is added.
  2. The gas produced is smelled cautiously (care)
  3. A piece of damp indicator paper can be held in the mouth of the test tube.
  4. A piece of filter paper is dipped into some starch/potassium iodide solution and held in the mouth of the test tube.



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Copyright: 2003 Isis Publication