Demonstration and combustion of acetylene

Chemicals needed

calcium carbide GSLEICHT.gif (932 Byte) F   R 15    S (2)-8-43

tap water

Dangerous substance information

acetylene GSLEICHT.gif (932 Byte) F+     R 5-6-12    S (2)-9-16-33

Equipment needed

glass funnel
short piece of rubber tube
glass tube with nozzle
source of fire or spark
wide beaker or a large crystallizing dish

Note (thanks to Desinfector): the danger of blowback can be markedly reduced if one stuffs the nozzle with a wad of steel wool!

Test procedure

Extinguish all flames! Provide for ventilation.

Preliminary Experiment



The contaminated water can be discharged into the drainage.


CaC2 + 2 H2O --> Ca(OH)2 + C2H2

Ca(OH)2 + CO2 --> CaCO3 + H2O

Water decomposes calcium carbide into calcium hydroxide and acetylene. Calcium hydroxide forms together with the carbon dioxide dissolved in water, insoluble calcium carbonate. In a side reaction toxic, foul hydrogen phosphide is formed by the hydrolysis of calcium phosphide, which occurs as an impurity in technical carbide.


DSCN0023.JPG (211745 Byte)

Calcium carbide (remove container before begin of experiment) and experimental apparatus

DSCN0025.JPG (210926 Byte)

Acetylene burns with a bright flame, the water is heavily clouded.

The experiment is a demonstration derived from my school lessons.