[bigbuffbossbaby]

Are molecules that contain hydrogen bonds always polar, even if they are symmetrical?

[Babcock_Hall]

Do you have an example in mind?

[bigbuffbossbaby]

Yes, ethylene glycol. It has hydrogen bonds but it is symmetrical in shape, so I was wondering if it would be considered polar or nonpolar.

[Babcock_Hall]

Can one ethylene glycol molecule form a hydrogen bond with another one?

[jeffmoonchop]

When you say 'it has hydrogen bonds' what do you mean? Do you mean it forms hydrogen bonds with itself (intramolecularly) or with other ethylene glycol molecules, or with anything? Because if you drop a molecule of ethylene glycol in pure hexane, it doesn't have hydrogen bonds.

[bigbuffbossbaby]

When I say "hydrogen bonds," I mean that it forms hydrogen bonds with water in a solution. So would it be considered polar or nonpolar?

[AWK]

Only one of the many conformations of ethylene glycol has no dipole moment. If you add a symmetrical system of hydrogen bonds to this, the compound still won't have a dipole moment.
But it is not a thermodynamically more persistent conformation. Additionally, the ethylene glycol will have a different conformation close to the surface of the solution and on the inside of the solution. Just because a solution has a certain concentration does not mean a conformation all solute molecules are identical.
If we consider monofunctional compounds with one polar group, e.g. alcohols with one OH group, acids with one carboxyl group, even without hydrogen bonds, individual molecules of these compounds will always have a dipole moment.
But a symmetrical dimer of two acid molecules (and such are present in solution at lower temperatures) linked by hydrogen bonds will not have a dipole moment.
For symmetrical compounds having two identical polar groups (i.e. having at least one conformation with the center of symmetry), there is no definite answer. The decisive factor is the symmetry of the molecules or molecular system and the symmetry of the hydrogen bond system.