Ethene (C₂H₄) and ethyne (C₂H₂) are unsaturated hydrocarbons - Leaving Cert Chemistry - Question 1 - 2006
Question 1
Ethene (C₂H₄) and ethyne (C₂H₂) are unsaturated hydrocarbons. They can both be easily prepared in a school laboratory.
(a) The diagram on the right shows an apparat... show full transcript
Worked Solution & Example Answer:Ethene (C₂H₄) and ethyne (C₂H₂) are unsaturated hydrocarbons - Leaving Cert Chemistry - Question 1 - 2006
Step 1
Identify solid A which is used to keep the ethane at the end of the test tube.
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Answer
Solid A is identified as glass wool or rock wool.
Step 2
Name the or formula of solid B which is heated using the Bunsen burner.
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Answer
Solid B is calcium carbide, represented as CaC₂.
Step 3
What precaution should be taken when heating is stopped? Why is this necessary?
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When heating is stopped, the delivery tube should be removed from the trough, which is necessary to prevent back suction of water into the apparatus.
Step 4
Give one major use of ethyne gas.
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Ethyne gas is primarily used for welding torches and cutting torches in metalworking.
Step 5
Identify solid X and liquid Y, the reagents used in this preparation.
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Solid X is calcium carbide (CaC₂), and liquid Y is water (H₂O).
Step 6
Describe what you would observe when a sample of ethyne gas is burned in air.
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When ethyne gas is burned in air, a luminous flame with soot is produced due to incomplete combustion.
Step 7
Give one major use of ethyne gas.
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Ethyne gas is used in the manufacturing of plastics and synthetic materials.
Step 8
Describe a test you could carry out on either of the two gases to show that it is unsaturated.
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You can add bromine solution to the gas. If it is unsaturated, the solution will decolourise, indicating the presence of double or triple bonds.
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