01 Ethene Gas

Summary

This educational video demonstrates the laboratory preparation of ethylene gas from ethanol. It outlines the necessary equipment, including a test tube with a sidearm and a Bunsen burner, and the use of aluminum oxide as a dehydrating agent. The script details the steps for heating, collecting ethylene, and conducting tests for unsaturation using acidified potassium permanganate and bromine water. It also explains how to identify ethylene gas through its bright blue flame test and the presence of carbon dioxide, verified by the milkiness of lime water.

Takeaways

• 🔬 The experiment involves the preparation of ethylene gas (C2H4) from ethanol.
• 🌡️ The process requires heating ethanol in the presence of aluminum oxide as a catalyst.
• 🧪 A test tube with a sidearm and a Bunsen burner are used for the reaction setup.
• 🔥 The aluminum oxide is heated to initiate the dehydration of ethanol to produce ethylene.
• 💧 Glass jars are used to collect the ethylene gas, and glass wool is used to support the ethanol inside the test tube.
• 🌬️ The initial bubbles produced are displaced air, not ethylene, which is collected once the air is displaced.
• 🧪 Lime water and acidified potassium permanganate are used to test for the presence of ethylene, indicating unsaturation by decolorization.
• 🔥 Ethylene gas burns with a bright blue flame, which is a characteristic test for its presence.
• 🌿 Bromine water is used to test for unsaturation, where ethylene gas decolorizes the bromine water due to the addition reaction across the double bond.
• ⚗️ The byproduct of the reaction is carbon dioxide, which is tested using lime water turning milky.

Q & A

What is the main reaction described in the script?

The main reaction described in the script is the preparation of ethene gas (C2H4) from ethanol (C2H5OH) through a dehydration process.

What is the role of ethanol in this reaction?

Ethanol serves as the starting material, which is dehydrated to form ethene gas and water.

What is the purpose of aluminum oxide in this reaction?

Aluminum oxide acts as a dehydrating catalyst to facilitate the removal of water from ethanol, leading to the formation of ethene.

Why is a tight-fitting Bunsen burner used in the reaction setup?

A tight-fitting Bunsen burner is used to ensure efficient heating of the reaction mixture and to prevent the escape of ethene gas.

What is the significance of glass wool in the reaction setup?

Glass wool is used to support the ethanol and prevent it from splashing out of the test tube during heating.

How is the presence of ethene gas confirmed in the script?

The presence of ethene gas is confirmed by testing for unsaturation using acidified potassium permanganate and bromine water, both of which should decolorize in the presence of ethene.

What is the purpose of the glass trough in the reaction setup?

The glass trough is used to collect ethene gas during the reaction, preventing it from escaping into the atmosphere.

Why is it important to remove the rubber tubing before moving the glass jar in the script?

Removing the rubber tubing before moving the glass jar prevents the formation of a vacuum inside the test tube, which could cause the test tube to shatter due to the contraction of gases upon cooling.

What is the test for the presence of carbon dioxide in the reaction?

The presence of carbon dioxide is tested by adding lime water to the reaction container; if carbon dioxide is present, the lime water will turn milky.

How is the ethene gas identified in the script?

Ethene gas is identified by its characteristic bright blue flame in a flame test.