The table shows the boiling points and structures of some isomers with molecular formula C6H12O2 - Scottish Highers Chemistry - Question 12 - 2016
Question 12
The table shows the boiling points and structures of some isomers with molecular formula C6H12O2.
Isomer 1
Structure
Boiling point (°C)
1
205
2
201
3
... show full transcript
Worked Solution & Example Answer:The table shows the boiling points and structures of some isomers with molecular formula C6H12O2 - Scottish Highers Chemistry - Question 12 - 2016
Step 1
Name the intermolecular force which accounts for the higher boiling points of isomers 1, 2 and 3.
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Answer
The intermolecular force responsible for the higher boiling points of isomers 1, 2, and 3 is hydrogen bonding. This type of bonding occurs when hydrogen is bonded to highly electronegative atoms such as oxygen, leading to strong attractions between molecules.
Step 2
Using the information in the table, describe two ways in which differences in structure affect the boiling points of isomeric esters 4-8.
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Answer
More branching lowers the boiling point: With increased branching in the carbon chain, the surface area decreases, resulting in weaker van der Waals forces and lower boiling points.
The position of functional groups affects boiling points: The nearer the ester link (–COO–) is to the ends of the carbon chain, the lower the boiling point tends to be, as this structural feature influences intermolecular forces.
Step 3
Predict the boiling point, in °C, for the isomer shown below.
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Answer
The predicted boiling point for the given structure, which resembles an ester, would be between 99 °C and 124 °C, specifically around 116 °C based on data trends observed.
Step 4
Label each peak in the ethyl ethanoate spectrum with a number to match the carbon atom in ethyl ethanoate.
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Answer
Peaks labeled in order: 2, 3, 1, 4.
Step 5
Determine the number of peaks that would be seen in the carbon-13 NMR spectrum for the ester shown below.
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Answer
There would be 5 peaks in the carbon-13 NMR spectrum for the ester.
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