What intermolecular forces are present in #C_2H_8O# (1-Propanol)?

#C_2H_8O#

1 Answer
Dec 6, 2016

Answer:

The most obvious one in #"hydrogen bonding"#.

Explanation:

One of the best indicators of intermolecular interaction is the normal boiling point. Molecules with significant intermolecular interaction tend to have higher boiling points. Water, a small molecule, has an exceptionally high boiling point because of intermolecular hydrogen bonding, which persists BETWEEN molecules:

#H-O^(delta-)-H^(delta+)cdotsO^(delta-)-H^(delta+)""_2#

Now #"1-propanol"# has a normal boiling point of #97-98# #""^@C#. And we compare this to that of #"isopropanol"#, #82.6# #""^@C#, and #"ethanol"#, #78.0# #""^@C.#

Given these data, there is another contributor to intermolecular interaction, and here it is the non-polar interaction between hydrocarbyl chains. The longer the chain, the greater the chain-chain interaction, and in long chain alcohols (and alkanes), boiling points will be elevated. Compare the boiling point of #"n-butanol,"# #117.7# #""^@C#, and #"n-pentanol,"# #137-139# #""^@C#.