Colorless rose

The red rose turns white in greenish fumes.

Scientific name: Chlorine oxidizes the red pigment in rose petals.


Colorless rose

by ChemToddler

chlorine generator bleaches a flower

by Breakthrough Boredom

Chlorine Bleaching

by kopmanchem1


Chlorine is a very toxic gas. Perform this experiment only in a fume hood. Wear eye protection goggles and gloves.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

Cl2 + red rose pigment → 2Cl- + reduced rose pigment (white)

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. This experiment should be performed only in a fume hood.
  2. Prepare a flask, chlorine source and a red rose.
  3. Attach one end of the gas delivery tube to the chlorine source. Put the other one down the flask.
  4. Fill the flask with chlorine.
  5. Place the rose into the flask. Cover the flask neck with a watch glass.
  6. After a while take out the flower. The rose turns white.

Scientific background

Anthocyanins are common pigments of many flowers. The red color of rose petals is caused by their presence. Chlorine is a strong oxidizer. It easily reacts with plenty of pigments and is usually used as a bleaching agent. Anthocyanins are reduced and turn the rose white.


Published on 15 June 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst