Rank the following compounds in order of increasing strength of intermolecular forces,putting the molecule with the weakest intermolecular force first.
A)I

Question

Rank the following compounds in order of increasing strength of intermolecular forces,putting the molecule with the weakest intermolecular force first. 
A)I < II < III 
B)II < I < III 
C)I < III < II 
D)II < III < I

Quizplus · Accepted Answer

The strength of intermolecular forces is mainly determined by the types of bond and molecule's size.

I) CH4: This molecule has only weak van der Waals forces between nonpolar molecules. The intermolecular forces only involve these weak van der Waals dispersion forces.

II) C2H5OH: This molecule has hydrogen bonding, caused by an H atom attached to an N, O, or F atom. Hence, C2H5OH molecules can make stronger intermolecular forces than CH4 through forming H-bonds.

III) CH3OCH3: This molecule also has a larger number of electrons that participate in van der Waals forces like CH4. But, as a larger molecule, CH3OCH3 molecules have stronger dispersion forces than CH4 because it has more electrons that participate in the van der Waals interactions.

Thus, the correct order of increasing strength of intermolecular forces is I < III < II.

Rank the Following Compounds in Order of Increasing Strength of Intermolecular