Banana oil, 3-methylbutylethanoate, CH₃COOCH₂CH(CH₃)₂, is a sweet smelling liquid that gives bananas their characteristic odour - VCE - SSCE Chemistry - Question 7 - 2011 - Paper 1
Question 7
Banana oil, 3-methylbutylethanoate, CH₃COOCH₂CH(CH₃)₂, is a sweet smelling liquid that gives bananas their characteristic odour.
A chemist working for Go Bananas P... show full transcript
Worked Solution & Example Answer:Banana oil, 3-methylbutylethanoate, CH₃COOCH₂CH(CH₃)₂, is a sweet smelling liquid that gives bananas their characteristic odour - VCE - SSCE Chemistry - Question 7 - 2011 - Paper 1
Step 1
i. Identify reagent A.
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Answer
Reagent A is sulfuric acid (H₂SO₄), which is commonly used as a catalyst in esterification reactions.
Step 2
ii. Compound B is an alcohol. Draw a structure of compound B.
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Answer
The structure of compound B, 3-methylbutanol, can be represented as:
CH₃
|
CH₃-CH-CH₂-OH
|
CH₃
Step 3
iii. Give the systematic name of compound B.
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The systematic name of compound B is 3-methylbutan-1-ol.
Step 4
iv. Give the systematic name of compound C.
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The systematic name of compound C is ethanoic acid.
Step 5
v. Identify reagent D.
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Reagent D is potassium dichromate (K₂Cr₂O₇) in acidic conditions, which is often used for oxidation reactions.
Step 6
vi. Which reaction is an oxidation reaction?
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Reaction II is the oxidation reaction, where alcohol (compound B) is oxidized to form ethanoic acid (compound C).
Step 7
Describe the principles of fraction distillation.
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Answer
Fractional distillation is a separation technique used to separate a mixture into its individual components based on differences in boiling points. The mixture is heated, and the component with the lowest boiling point vaporizes first. This vapor is then cooled and condensed back into a liquid, collected separately. The process can be repeated (fractionated) to improve separation, relying on the fact that components with closer boiling points can be separated by controlling the temperature and using a fractionating column.
Step 8
Explain how the evidence provided by these spectra supports the chemist’s claim.
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Answer
The IR spectra of the distilled banana oil and pure compound B should show significant differences, indicating the successful separation of the two components. For example, the presence of characteristic peaks for functional groups should be evident in the sample of banana oil but absent in the spectrum of compound B. This change in spectral data implies that the distillation process effectively removed compound B, proving a complete separation as claimed by the chemist.
