demonstrations:acetylene_from_calcium_carbide

Acetylene From Calcium Carbide

Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★★ Requires a more experienced teacher
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Combustion, Gases

Alternative titles: Combustion of Acetylene

Summary

Acetylene gas is generated by reacting calcium carbide with hydrochloric acid.

Procedure

  1. Place small pieces of calcium carbide in a flask fitted with a delivery tube.
  2. Add water slowly to the flask to initiate the reaction.
  3. Collect the gas evolved (acetylene) by downward displacement of water.
  4. Use the gas immediately, as acetylene is unstable and highly flammable.

Laboratory Preparation of Acetylene (C2H2) Gas | CBSE Syllabus - Practical Science:


Lab. preparation of ACETYLENE gas - Practical CHEMISTRY | Flammable Gas - Science Sir:


📄 Spontaneous Combustion of Acetylene - UC San Diego: https://www-chem.ucsd.edu/undergraduate/teaching-labs/demos/demo22.html

Variations

  • Show the combustion of acetylene in air to demonstrate its sooty flame.
  • Compare acetylene combustion with methane combustion to highlight differences between alkyne and alkane burning.
  • Use acetylene in a reaction with chlorine (under safe, controlled conditions) to illustrate reactivity.

Safety Precautions

  • Wear safety goggles, gloves, and a lab coat.
  • Handle calcium carbide carefully; it reacts violently with water to release flammable gas.
  • Perform the reaction in a well-ventilated area or fume hood.
  • Keep all flames and ignition sources away from acetylene until intended combustion.
  • Dispose of calcium hydroxide residue safely as basic waste.

Questions to Consider

  • What happens when CaC₂ reacts with water? (It produces acetylene gas and calcium hydroxide.)
  • What is the balanced chemical equation? (CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂.)
  • What type of chemical reaction is this? (Hydrolysis reaction.)
  • What are some uses of acetylene gas? (Welding, production of organic compounds, laboratory demonstrations.)
  • Why must acetylene be collected and used immediately? (It is unstable and highly flammable.)