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Ethene can be prepared in the school laboratory using the arrangement of apparatus shown in Diagram 1 - Leaving Cert Chemistry - Question 2 - 2009

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Ethene can be prepared in the school laboratory using the arrangement of apparatus shown in Diagram 1. Ethylene can be prepared in the school laboratory using the ar... show full transcript

Worked Solution & Example Answer:Ethene can be prepared in the school laboratory using the arrangement of apparatus shown in Diagram 1 - Leaving Cert Chemistry - Question 2 - 2009

Step 1

Give the name of chemical formula of the solid X used in the preparation of ethene. What is the colour of this solid?

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Answer

The chemical formula of solid X is calcium carbide, represented as CaC2. The colour of this solid is typically grey, dark grey, or black.

Step 2

Write a balanced equation for the reaction involved in the preparation of ethene. What term describes this type of reaction?

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Answer

The balanced equation for the preparation of ethene from calcium carbide and water is:

ightarrow ext{C}_2 ext{H}_4 + ext{Ca(OH)}_2$$ This type of reaction is termed an 'elimination reaction' (or dehydration reaction).

Step 3

State three procedures that should be observed when carrying out the preparation of ethene by this method.

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Answer

  1. Ensure that the apparatus is securely connected and avoid inhaling glass wool by wearing a mask.
  2. Keep the apparatus away from flames to prevent any accidental fires.
  3. Use safety glasses or goggles during the experiment for eye protection.

Step 4

Give the name or formula of the solid Y used in the preparation of ethene in the school laboratory. Describe the appearance of this solid.

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Answer

The solid Y used in the preparation of ethene is calcium hydroxide, with the formula Ca(OH)2. It typically appears as a colourless or white solid.

Step 5

Both ethene and ethyne are described as unsaturated. What does this mean? Describe a test you could carry out to show that ethyne (which is the solid you said is unsaturated) is unsaturated. What would you observe during the test?

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Answer

Being unsaturated means that the molecules contain double or triple bonds, allowing them to undergo addition reactions. A test for ethyne (C2H2) would involve adding bromine water, where a decolorization would be observed, indicating the presence of unsaturation.

Step 6

Both ethene and ethyne can be burned. What is the most noticeable difference seen when these combustions are carried out? Write a chemical equation for the complete combustion of either gas.

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Answer

The most noticeable difference during the combustion is that ethyne produces a sootier flame compared to ethene due to its triple bond. The complete combustion reaction for ethene is:

ightarrow 2 ext{CO}_2 + 2 ext{H}_2 ext{O}$$

Step 7

Give: i) a major use of ethene.

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Answer

i) A major use of ethene is in the production of polyethylene, which is a widely used plastic.

Step 8

ii) a major use of ethyne.

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Answer

ii) A major use of ethyne, also known as acetylene, is in welding and cutting applications due to its high flame temperature.

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