Ethylene/Ethene gas (C2H4) is prepared by catalytic dehydration of ethanol using aluminum oxide. The gas can then be tested for unsaturation by its reaction with iodine water, showing the reactivity of alkenes.

1. Place aluminum oxide catalyst in the center of a test tube or small glass reaction tube.
2. Clamp the tube horizontally and connect the outlet to a gas collection system (such as water displacement).
3. Add ethanol dropwise to the heated catalyst using a dropping funnel or cotton wool soaked in ethanol.
4. Heat the aluminum oxide catalyst gently to drive the dehydration reaction.
5. Collect the ethylene gas as it is produced.
6. Test the gas by bubbling it through iodine water (or bromine water if available). Observe the decolorization, which indicates the presence of a carbon–carbon double bond.

How to Make Ethene (Ethylene) - Catalytic Dehydration of Ethanol - TheChemistryShack:

Preparation of Ethene - Pdst Chemistry:

• Test ethylene with alkaline potassium permanganate solution (Baeyer’s test) to show the formation of a diol.
• Use ethylene to ripen bananas, test with a control.

• Wear safety goggles, gloves, and a lab coat.
• Perform the experiment in a well-ventilated area or fume hood; ethene is flammable.
• Keep ethanol and ethylene away from open flames.
• Handle hot glassware and catalysts with care to avoid burns.
• Dispose of halogen water and chemical residues according to laboratory safety protocols.

• What type of reaction converts ethanol to ethene? (Dehydration, a type of elimination reaction.)
• Why is aluminum oxide used in this experiment? (It acts as a catalyst to lower the activation energy for dehydration.)
• How does the test with iodine or bromine water confirm the presence of a double bond? (The halogen adds across the double bond, removing the color of the solution.)
• What industrial uses does ethene have? (Polymer production, alcohol synthesis, ripening agent for fruit.)