Production and Combustion of Acetylene Gas

Purpose:

To demonstrate the generation and flammability of acetylene gas through a solid reacting with water.

Materials:

• Long candle
• Metal bowl

Reagents:

• Calcium carbide (CaC_2(s))

Hazards and PPE:

• Acetylene is highly flammable. Do not stand too close to metal bowl when igniting acetylene gas.
• Calcium carbide produces flammable acetylene gas upon contact with water. The calcium carbide may contain a contaminate resulting in the release of the toxic gas phosphine on contact with water. Be sure to use non-contaminated, fresh calcium carbide.
• Wear approved safety goggles and gloves.

Protocol:

Demonstration

1. Add ~10g of CaC_{2 (s)} to metal bowl. Add more CaC_{2 (s)} if you want the reaction to last longer.
2. Add 2-3 mL DI H₂O to metal bowl to begin acetylene gas production.
3. Light the candle.
4. Carefully and quickly hold the flame over the burning CaC_{2 (s)} to ignite the acetylene gas. A large flame will be produced.
   1. Add more H₂O to the metal bowl to increase the intensity of the flame.

Disposal:

• Add excess water to calcium carbide until bubbling ceases. Do this in the hood due to acetylene gas production.
• Place solid products in appropriate container and pour leftover liquid down the drain with excess water.

Reactions:

• CaC_{2 (s)} + 2H₂O_(l) → C₂H_2(g) + Ca(OH)_2(aq)

Citations:

1. This demo adapted from the demo library of the Chemistry department at the University of Illinois at Urbana-Champaign.

Videos:

• Calcium Carbide and Water & Combustion of Acetylene

  Anne Schmidt

  This version of the demonstration uses ice instead of DI water, which slows the reaction but risks the introduction of contaminants.