Which of the Following Statements is True of London Dispersion

Question

Which of the following statements is true of London dispersion forces?
A) London dispersion forces are stronger between the molecules of 1-butanol than between the molecules of 2-methyl-2-propanol.
B) London dispersion forces are weaker than hydrogen bonding interactions.
C) London dispersion forces are stronger between the molecules of 1-butanol than between the molecules of 2-methyl-2-propanol and are weaker than hydrogen bonding interactions.
D) None of these

Accepted Answer

London dispersion forces are the weakest intermolecular force and occur between all molecules. However, they are dependent on the size and shape of a molecule. In this case, 1-butanol is larger than 2-methyl-2-propanol and has more surface area for the formation of London dispersion forces. Therefore, London dispersion forces are stronger between the molecules of 1-butanol than between the molecules of 2-methyl-2-propanol. Hydrogen bonding interactions are stronger than London dispersion forces but only occur between molecules that contain hydrogen bonded to nitrogen, oxygen or fluorine. 1-butanol has a hydroxyl group, which can participate in hydrogen bonding, making this intermolecular force stronger than the London dispersion forces between 1-butanol molecules.