A straight-chained alkane has a molar mass of 72.146 g mol⁻¹ - HSC - SSCE Chemistry - Question 24 - 2021 - Paper 1
Question 24
A straight-chained alkane has a molar mass of 72.146 g mol⁻¹.
Provide the structural formulae for this alkane and all other isomers of it in the space provided.
Na... show full transcript
Worked Solution & Example Answer:A straight-chained alkane has a molar mass of 72.146 g mol⁻¹ - HSC - SSCE Chemistry - Question 24 - 2021 - Paper 1
Step 1
Provide the structural formula for the straight-chained alkane (Pentane)
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Answer
The structural formula for pentane (C₅H₁₂) is:
H H H H H
| | | | |
H--C---C---C---C---C--H
| | | | |
H H H H H
This shows a linear arrangement of five carbon atoms.
Step 2
Name and provide structural formula for 2-methylbutane
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Answer
2-methylbutane is another isomer of pentane. Its structural formula is:
H H H
| | |
H--C---C---C--H
| | |
H C---H
| |
H H
Here, one of the carbon atoms of butane is replaced by a methyl group (−CH₃).
Step 3
Name and provide structural formula for 2,2-dimethylpropane
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Answer
2,2-dimethylpropane is another isomer. Its structural formula is:
H H
| |
H--C---C--H
| | |
H C---C--H
|
H
In this structure, two methyl groups are attached to the second carbon of propane.
