Properties and Uses of Unsaturated Hydrocarbons

Question 6 • CT-Chemistry B

Did your answers include all of the following?

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

All five statements describe the effect of increasing carbon-chain length. 1-pentyne is smaller than 1-octyne, so it has a lower boiling point; likewise, smaller 1-butene is more volatile and has a higher vapor pressure than 1-heptene at the same lower temperature. Larger molecules have stronger London dispersion forces, which generally raises their boiling points and means more energy is needed to vaporize them. These trends result from differences in molecular size and chain length.

AI-written and checked against the verified answer.

Back to All Questions

More from this Course

Instruction

Instruction

Assignment