Laboratory Preparation of Acetylene Gas from Calcium Carbide (CaC₂)
22nd Nov 2024
Experiment 79
Objective
To prepare acetylene gas (CH≡CH) in the laboratory by reacting calcium carbide (CaC₂) with water.
Introduction
Acetylene (C₂H₂) is a hydrocarbon gas characterized by a triple bond between two carbon atoms. When calcium carbide reacts with water, it produces acetylene gas along with calcium hydroxide as a byproduct.
Reaction
CaC2 + 2H2O→ C2H2 + Ca(OH)2
Materials
Chemicals
· Distilled water
· Calcium carbide (CaC₂)
· Sulfuric acid (H₂SO₄)
· Copper sulfate solution (CuSO₄)
Apparatus
· Flask
· Sand
· Funnel
· Elimination tube
· Ethylene gas collector bottle
· Spirit lamp
Reagents
· Prepare a solution of CuSO₄, H₂SO₄, and water to purify the gas by removing hydrogen sulfide and other contaminants.
Procedure
1. Preparation of Flask
o Place a layer of sand in the flask.
2. Addition of Calcium Carbide
o Place small pieces of calcium carbide into the flask.
3. Setup for Gas Collection
o Insert a funnel and an elimination tube into the mouth of the flask.
o Connect the end of the elimination tube to a bottle containing the CuSO₄, H₂SO₄, and water solution, ensuring the tube is submerged in the solution for purification.
4. Preparation of Gas Collection Bottle
o Place the gas collector bottle in position to collect the ethylene gas.
5. Reaction Initiation
o Add distilled water dropwise to the calcium carbide in the flask. The reaction between calcium carbide and water will generate acetylene gas.
6. Gas Purification
o The gas flows through the CuSO₄, H₂SO₄, and water solution to remove impurities and obtain purified acetylene gas.
Observation
The generated acetylene gas is collected in the gas collector bottle, displaying the properties typical of acetylene.
Questions
1. What is ethylene gas?
2. What is the structure of acetylene gas?
3. What reaction occurs when calcium carbide and water are combined?
4. How can 100% purified acetylene be obtained?