Chemical smoke

A smoke magically appears when two glasses are put close to each other

Scientific name: The diffusion of hydrogen chloride and ammonia gas through air to form ammonium chloride smoke


HCl+NH3=NH4Cl - Ammonium chloride smoke under 100,000,000x microscope

by MEL Science

Ammonium chloride fog experiment No. 10 - Ammoniumchlorid Nebel Versuch Nr. 10

by Facer91

Make Ammonium Chloride

by myst32YT

A Gas Phase Reaction: Producing Ammonium Chloride

by mrhomescientist

Smoke with ammonia and hydrochloric acid

by chemlabchemistry


by Basco36

Ammonium Chloride HCl + NH3 = NH4Cl Hydrochloric acid + ammonia hydroxide.

by TheBackyardScientist


Both used liquides concentrated ammonia solution and concentrated hydrochloric acid are very corrosive. If either of these liquids comes into contact with your skin, flush with copious amounts of water. Wear goggles. If you get some in you eyes, immediatly flush with water for at least 15 minutes and seek medical attention. Vapors of both the used liquides are dangerous. Avoid breathing the vapors.

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

Reaction formula

HCl + NH3 → NH4Cl↓

Step-by-step instruction

  1. Place two containers with hydrochloric acid and ammonia solution next two each other.
  2. Both hydrochloric acid and ammonia solution should be concentrated or close to concentrated otherwise evaporation would be too slow.
  3. You can also moisten a glass with hydrochloric acid and a moisten a flat surface with ammonia solution then place the glass on this surface upside down and smoke would appear inside the glass.

Scientific background

Hydrogen chloride and ammonia are gases at room temperature. They are highly soluble in water. Dissolved molecules easily pass into air from the concentrated solution. In the gas phase, molecules readily extend beyond the vessels. Ammonia and hydrogen chloride molecules react to form a new molecule called ammonium chloride. Separate molecules of ammonia chloride combine together to form a crystal. A small crystal nucleus grows bigger and bigger as new molecules of ammonia chloride join to it. Sometimes a couple of small crystals combine together giving a greater one. These new crystals can combine in their turn and so on. This process continues until particles become several thousandths of a millimeter in diameter. These particles form the smoke that we can see.


Published on 21 August 2014

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