1. Ethene and ethyne are both unsaturated, gaseous, flammable hydrocarbons - Leaving Cert Chemistry - Question 1 - 2016
Question 1
1. Ethene and ethyne are both unsaturated, gaseous, flammable hydrocarbons.
(a) The diagram shows the preparation and collection of ethene (C₂H₄).
(i) Identify liq... show full transcript
Worked Solution & Example Answer:1. Ethene and ethyne are both unsaturated, gaseous, flammable hydrocarbons - Leaving Cert Chemistry - Question 1 - 2016
Step 1
Identify liquid A held by glass wool at the end of the horizontal test tube.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Liquid A is identified as ethanol (C₂H₅OH).
Step 2
Give the name or formula of the white solid B.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The white solid B is aluminium oxide (Al₂O₃).
Step 3
State one precaution that should be taken while carrying out this preparation.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One precaution is to avoid fire by keeping the Bunsen burner at a safe distance from the apparatus as ethene is flammable.
Step 4
Describe how ethene could be tested for unsaturation.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To test for unsaturation, ethene can be bubbled through bromine solution or potassium permanganate solution. A color change indicates the presence of double bonds: the bromine solution changes from orange to colorless, or the permanganate solution changes from purple to colorless.
Step 5
Write a balanced equation for the complete combustion of ethene in oxygen.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
ightarrow 2CO_2 + 2H_2O$$
Step 6
Identify solid X.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Solid X is calcium carbide (CaC₂).
Step 7
Describe how a combustion test on a sample of ethyne supplied in a stoppered test tube could be carried out.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To carry out the combustion test, one should quickly unstop the test tube and briefly ignite the ethyne with a splint or lighter, while covering the opening to allow gas to accumulate.
Step 8
What would be observed?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The observation would be a sooty flame with a luminous (yellow) appearance due to incomplete combustion.
Step 9
Give one major use for ethyne.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One major use for ethyne is in cutting metals and for ripening bananas using an oxyacetylene torch.
Join the Leaving Cert students using SimpleStudy...
