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The diagram shows the experimental set-up used by a group of students to prepare a sample of ethene from ethanol and to collect the ethene produced - Leaving Cert Chemistry - Question 2 - 2004
Question 2
The diagram shows the experimental set-up used by a group of students to prepare a sample of ethene from ethanol and to collect the ethene produced. (a) What is the... show full transcript
Worked Solution & Example Answer:The diagram shows the experimental set-up used by a group of students to prepare a sample of ethene from ethanol and to collect the ethene produced - Leaving Cert Chemistry - Question 2 - 2004
Step 1
What is the function of the glass wool? Identify the solid X and describe its appearance.
Answer
The glass wool serves to keep the ethanol at the end of the test tube, allowing it to soak up the liquid effectively without wetting the aluminum oxide (or solid X). Solid X is aluminum oxide (Al₂O₃), which appears as a white powder. Its role is to act as a catalyst in the reaction.
Step 2
State and explain two safety precautions which should be observed when carrying out the student experiment.
Answer
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Keep gas away from flames: Ethene is flammable, and exposure to flames poses a risk of explosion. Therefore, all flammable materials should be kept away from the experimental setup.
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Use safety goggles: Wearing safety goggles is essential to protect the eyes from any splashes or accidental exposure to chemicals.
Step 3
Step 4
What is meant by the term unsaturated? Describe how you would carry out another test to confirm that ethene is unsaturated.
Answer
The term 'unsaturated' refers to compounds that contain double or triple bonds, indicating that they can react with additional atoms or molecules. To confirm ethene is unsaturated, I would carry out a test by adding bromine water. If the bromine water decolourises from red to colourless, this indicates that ethene reacts with bromine, confirming its unsaturation.
Step 5
Describe the flame that would be observed when a combustion test is carried out on a sample of ethene gas. Write a balanced equation for the combustion of ethene in excess oxygen.
Answer
When a combustion test is performed on ethene, a pale blue flame with a slightly smoky appearance would be observed, indicating incomplete combustion. The balanced equation for the combustion of ethene in excess oxygen is: