Ethyne gas is prepared by the reaction of water with calcium carbide (CaC2). Ethyne gas is a colourless gas.

Main Chemicals required

  • Calcium Carbide (CaC2) [also known as calcium dicarbide] – A white/gray solid
  • Acidified copper (II) sulfate solution
  • Water


  1. Set up the apparatus as shown in the diagram.
  2. Place few pieces of calcium carbide in a Büchner flash.
  3. Add water from the dropping funnel, few drops at a time.
  4. Collect the gas produced in the test tube.
  5. Discard the first test tube as it a mixture of air and ethyne.


The ethyne gas burns with a luminous smoky flame with soot as a result of unburnt carbons.

Addition of Bromine Test

  • Bromine water turns from yellow/red colour to colourless.
  • The decolorisation of bromine is the standart test for unsaturation in a compound.

Addition of Acidified Potassium Permanganate (KMnO4) Test

  • Purple colour to colourless.
  • This is also used to test for presence of a C ≡ C triple bond (unsaturation).

Video Demonstration

What is its industrial application

what are the chemical reactions between ethyne gas with bromine water,and potassium permanganate and also the reaction of happens when ethyne gas burns with air