Physical Chemistry : Intermolecular Forces

Study concepts, example questions & explanations for Physical Chemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 : Identifying Intermolecular Forces

Which of the following forces is considered the weakest?

Possible Answers:

Dipole-dipole interactions

Hydrogen bonding

Ionic bonding

London dispersion forces

Correct answer:

London dispersion forces

Explanation:

The intermolecular forces from strongest to weakest are ionic, hydrogen bonding, dipole-dipole, then London dispersion forces. All compounds experience some form of London dispersion force, but the force only becomes relevant if no other forces are contributing to the attraction of molecules or atoms.

Example Question #2 : Identifying Intermolecular Forces

Which intermolecular force will be the most powerful in a sample of ethanol 

Possible Answers:

Dipole-dipole interactions

Hydrogen bonding

London dispersion forces

Ionic bonding

Correct answer:

Hydrogen bonding

Explanation:

Ethanol will not form ions in solution, so we are left with the other three options as plausible answers. Of the three, the strongest force is hydrogen bonding, which only occurs if a hydrogen is directly attached to a nitrogen, oxygen, or fluorine in the molecule. Ethanol has a hydrogen attached to an oxygen, and is thus capable of hydrogen bonding.

Learning Tools by Varsity Tutors