Question 3

The relationship between boiling point and the number of carbon atoms in straight
chain molecules of aldehydes, alkanes and primary alcohols is investigated. Curves A,
B and C are obtained.

3.1 Define the term boiling point. (2)

3.2 Write down the STRUCTURAL FORMULA of the functional group of the
aldehydes. (1)

3.3 The graph shows that the boiling points increase as the number of carbon
atoms increases. Fully explain this trend (3)

3.4 Identify the curve (A, B or C) that represents the following:

3.4.1 Compounds with London forces only (1)

3.4.2 The aldehydes
Explain the answer. (4)

3.5 Use the information in the graph and write down the IUPAC name of the
compound with a boiling point of 373 K. (2)

3.6 Write down the IUPAC name of the compound containing five carbon atoms,
which has the lowest vapour pressure at a given temperature. (2)

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