Complete the sentence by putting a cross (\u2718) in the box next to your answer - Edexcel - GCSE Chemistry - Question 4 - 2016 - Paper 1
Question 4
Complete the sentence by putting a cross (\u2718) in the box next to your answer.
Alkenes are
A\u200b\u200bsaturated carbohydrates
B\u200b\u200bsaturated hydrocar... show full transcript
Worked Solution & Example Answer:Complete the sentence by putting a cross (\u2718) in the box next to your answer - Edexcel - GCSE Chemistry - Question 4 - 2016 - Paper 1
Step 1
Complete the sentence by putting a cross (\u2718) in the box next to your answer.
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Answer
Alkenes are D: unsaturated hydrocarbons. Unsaturated hydrocarbons contain at least one double bond between carbon atoms.
Step 2
(i) Draw the structure of a propene molecule, showing all of the bonds.
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Answer
The structure of propene (C₃H₆) is as follows:
H H H
\ / |
C = C
/ \
H C
/ \
H H
This shows a double bond between the first two carbon atoms and single bonds with the hydrogen atoms.
Step 3
(ii) Describe a test carried out on both gases to show which gas is propane and which gas is propene.
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Answer
To distinguish between propane and propene:
Add bromine water (or solution) to both gas samples.
Propene, being an alkene, will turn the bromine solution colorless (decolourises), indicating the presence of a double bond.
Propane, being an alkane, will not change the color of the bromine solution and will remain colorless.
