Burning of copper in sulfur vapour

A copper wire burns in brown vapour of sulfur

Scientific name: Red-hot copper wire burns in sulfur vapour, forming copper (I) sulfide


V85 Copper and Sulfur Reaction-Kupfer/Schwefel Reaktion

Взаимодействие серы с медью

by Уфа Химик

Горение меди в парах серы


This experiment must be performed in a well ventilated room or in a fume hood. Wear eye protection.

Avoid inhaling the sulfur vapours.

There is a serious fire risk - a fire extinguisher should be ready.

Make sure there is nothing flammable nearby.

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

Reaction formula

2Cu + S → Cu2S


  1. Copper wire
  2. Sulfur

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. Put sulfur powder (or pieces of sulfur) into a test-tube. Approximately 4/5 of the test-tube should be filled with sulfur.
  2. Set the test-tube in a clamp at an angel.
  3. Heat the test tube with a burner. At first sulfur melts, and then starts to boil. Heat the whole test-tube to vaporize sulfur which condensed on the wall of the tube. There should be a blue flame of the sulfur vapour near the open end of the tube.
  4. At the same time heat a copper wire until it glows red and put in the test-tube. After a few seconds the copper wire burns in the sulfur vapour.

Scientific background

Copper doesn't burn in air or in oxygen, but it can burn in sulfur vapours.

Heating the copper wire and an intensive stream of the sulfur vapours are needed to initiate this reaction. A black copper sulfide (Cu2S) is produced in this reaction.

Hold the copper wire with tweezers in the upper part of the test-tube for a better demonstration and to make sure the tube doesn’t crack (this can occur if the copper wire falls to the bottom of the test-tube).


Published on 01 April 2015

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