Question

Compare the boiling points of 1-pentyne and 1-octyne.

Answer 1

1-pentyne consists of a carbon chain of 5 carbons one with a triple bond. 1-octyne is a carbon chain of 8 carbons with a triple bond at some point. It is known that the longer the carbon chain the higher the boiling point since more energy will be required to break the bonds between carbons. Based on this it is predicted that 1-octyne will have a higher boiling point than 1-pentyne.

Answer 2

Answer:

1-pentyne has a lower boiling point than 1-octyne.  

1-butene has higher vapor pressures at lower temperatures than 1-heptene.  

The differences in boiling points and vapor pressures result from differences in the chain lengths of the molecules.

 Larger molecules have stronger intermolecular forces of attraction than smaller molecules.

More energy is required to move larger molecules into the vapor phase from the liquid state.

Explanation: