Barking dog

The wave of blue light spreads along the tube filled with carbon disulphide and nitrogen monoxide gases and is accompanied with a barking sound

Scientific name: Carbon disulphide reacts with nitrogen monoxide forming nitrogen, carbon monoxide, carbon dioxide, sulphur dioxide and sulphur.


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Wear eye protection goggles and gloves. This is a violent reaction. Keep a safe distance. There is a some fire risk - a fire extinguisher should be ready.

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

Reaction formula

32NO + 8CS2 → 16N2 + 8CO2 + 8SO2 + S8

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. Prepare a large glass tube with stoppers.
  2. Fill the tube with nitrogen monoxide gas.
  3. Add about 6-8 ml of carbon disulphide.
  4. Mix the components.
  5. Put the tube in a safety screen.
  6. Ignite gases in the tube.
  7. The mixture burns with a bright blue flame which moves along the tube.

Scientific background

In the experiment Barking dog carbon disulphide reacts with nitrogen monoxide NO as follows:

32 NO + 8 CS2 → 16 N2 + 8 CO2 + 8 SO2 + S8

Nitrogen monoxide is used as a source of oxygen to burn the carbon disulphide molecule. The reaction is highly exothermic and is accompanied with emission of bright blue light. The origin of this light is burning sulfur which is formed in the reaction. As the flame goes down the tube it accelerates itself. The gas under the flame front is compressed. At some point depending on the length of the tube it expands rapidly with barking or woofing sound.


Published on 04 March 2015

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