Question

Intermolecular forces determine the state of matter for a substance. All of the following substances are gases at room pressure and temperature.Which of the following compounds contains the weakest intermolecular forces?

• A. Ethane $\left(C{H}_{3}C{H}_3\right)$
• B. Nitrogen trifluoride
• C. Sulfur dioxide
• D. Ammonia

Answer 1

Answer: (A)

Ethane $\left(C{H}_{3}C{H}_3\right)$

$N{F}_3$ - dipole-dipole predominates because it is polar

$N{H}_3$ - predominant force is hydrogen bonding

Intermolecular Forces: Sulfur Dioxide is a non-polar molecule. Therefore it will hold weak London Dispersion forces in which instantaneous dipoles are formed in the atoms and between the molecules due to the amount of electrons.

Ethane is non-polar, and subject only to dispersion forces. So it has weakest intermolecular force.