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Study the reaction scheme and answer the questions which follow - Leaving Cert Chemistry - Question 8 - 2007
Question 8
Study the reaction scheme and answer the questions which follow. C₂H₄ → C₂H₅OH ⇌ CH₃CHO (a) Name the homologous series (i) to which A belongs, (ii) to which C belo... show full transcript
Worked Solution & Example Answer:Study the reaction scheme and answer the questions which follow - Leaving Cert Chemistry - Question 8 - 2007
Step 1
Step 2
The conversion of B to A is an elimination reaction. What two features of elimination reactions are illustrated by this conversion?
Answer
Two key features of elimination reactions illustrated in the conversion of B to A are:
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Loss of a small molecule: This reaction involves the removal of a small molecule, such as water or hydrogen halide, indicating an elimination reaction.
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Formation of an unsaturated compound: The conversion results in the formation of the alkene (A), which is unsaturated due to the presence of a carbon-carbon double bond.
Step 3
Step 4
Draw full structural formulas for B and C. Indicate any carbon atom in either structure that has planar geometry. List the bonds broken in B and the bond made in C in the synthesis of C from B.
Answer
The structural formulas are as follows:
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B (C₂H₅OH):
H H
| |
H-C-C-O-H
| |
H H -
C (CH₃CHO):
H O
| || H-C—C=O |
H
Indicate planar geometry:
The carbon atom in C (the one double-bonded to oxygen) is planar.
Bonds broken in B:
- C—O bond (removal of OH)
Bond made in C:
- C=C bond.
Step 5
After carrying out a laboratory conversion of B to C, how could you test the product to confirm the formation of C?
Answer
To confirm the formation of compound C (CH₃CHO), you could apply the following tests:
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Test with Fehling's solution: A positive result would show a color change to red, indicating the presence of an aldehyde.
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Test with 2,4-dinitrophenylhydrazine: The formation of an orange or yellow precipitate would confirm the presence of the carbonyl functional group.
Step 6
Compound C is formed as a metabolite of compound B in the human body. How does compound B come to be present in the body?
Answer
Compound B (C₂H₅OH) is commonly ingested through the consumption of alcoholic beverages. Ethanol is rapidly absorbed into the bloodstream and metabolized in the liver, resulting in the production of various metabolites, including acetaldehyde (compound C). Additionally, it can also be formed through metabolic processes involving sugars.