Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

Crude oil consists of a mixture of many hydrocarbons with molecules containing from 1 to 40 carbon atoms. The alkanes present in crude oil may be separated since their boiling points are not the same. The table gives the boiling points of several alkanes. What is the correct explanation for why the boiling points differ for the three isomers with $M_r = 72$?

  • ABoiling point is dependent upon the length of the carbon chain only.
  • BIncreased branching on a carbon chain increases the boiling point.
  • CIncreased branching reduces the strength of the intermolecular hydrogen bonding.
  • DIncreased branching reduces the strength of the intermolecular van der Waals’ forces.

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