Structural Isomerism
Intro to Organic Worksheet
Isomerism Questions
1. Define the term structural isomerism.
When multiple molecules have the same molecular formula but a different structural formula.
2. Draw the skeletal formulae and name for the isomers of pentane (not including pentane).
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Methylbutane -
Dimethylpropane
3. Draw the skeletal formulae and name for the isomers of pentene (including pentene).
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Pent-1-ene -
Pent-2-ene -
3-methylbut-1-ene -
2-methylbut-1-ene -
2-methylbut-2-ene -
Cyclopentane
4. There are many isomers of methyl butanoate.
a) Draw two positional isomers of methyl butanoate (not including methyl butanoate)
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Ethylpropanoate -
Propylethanoate -
Butylmethanoate
b) Draw a chain isomer of methyl butanoate.
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Methyl-2-methylpropanoate
c) Draw a functional group isomer of methyl butanoate.
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Pentanoic acid -
5-hydroxypentanal (or other positions for the two functional groups)
d) Out of question 4a, 4b and 4c, state which isomer will have the biggest difference in properties when compared to methyl propanoate.
The functional group isomers will have the biggest difference in properties as the Chemical properties are dependent on the functional group.
5. The boiling point of butane is -1.0oC. Predict whether the boiling point of methylpropane will be higher or lower than the boiling point of butane. Explain your answer.
Methylpropane will have a lower boiling point than butane. Although they have the same molecular formula, and therefore the same number of electrons, molecules of butane pack better. This results in more surface area in contact and therefore stronger Van Der Waals forces.