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Physical properties and separation of hydrocarbons

Organic chemistry • Carbon compounds as fuels

Key concepts

What you'll likely be quizzed about

  • Boiling point rises with increasing hydrocarbon size due to greater surface area and stronger London dispersion forces.
  • Larger molecules experience stronger intermolecular attractions, necessitating more thermal energy to convert liquid to vapor.
  • Branching reduces boiling point relative to straight-chain isomers by decreasing surface contact and dispersion forces.
  • External factors, such as pressure, also impact boiling points; lower pressure decreases boiling points while higher pressure increases them.

Flashcards

Test your knowledge with interactive flashcards

How does a fractionating column produce separation?

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A fractionating column creates temperature gradients and surfaces for multiple cycles of evaporation and condensation, enriching vapor with lighter compounds upwards.

Key notes

Important points to keep in mind

Boiling point increases with molecular size due to stronger London forces.

Branching lowers boiling point by reducing surface contact.

Viscosity increases with molecular size due to chain entanglement.

Higher temperature reduces viscosity by overcoming intermolecular forces.

Flammability declines with molecular size because larger molecules vaporize less easily.

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