Burning Sulphur with flower

The red rose turns white.

Scientific name: Sulfur dioxide oxidizes the red pigment in rose petals.

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Restore a rose | Sulphur | Chemistry

Free Range Chemistry 22 - Burning Sulphur with Rose

Safety

Sulphur dioxide 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

S + O2 → SO2

2S + 3O2 → 2SO3

SO2 + red rose pigment → SO42- + reduced rose pigment (white)

Reagents

  1. Anthocyanin
  2. Sulfur

Step-by-step instruction

  1. This experiment should be performed only in a fume hood.
  2. Place some sulfur into the ceramic cup.
  3. Put the cup into the large beaker.
  4. Prepare a red rose. Attach a wire to the flower’s stem.
  5. Hang the flower inside the beaker.
  6. Ignite the sulfur and cover the beaker with a glass.
  7. 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. When sulfur burns it produces sulfur dioxide and sulfur trioxide. Sulfur dioxide acts like a bleaching agent. It oxidizes anthocyanins and turns the rose white.

Danger:
Coolness:
Difficulty:

Published on 15 June 2015

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