Question

Could anyone explain why the molecular weight of acetic acid vapor becomes 120 g/mol?

Answer 1

perhaps anyone could explain how this is possible?

Answer 2

I understand that because, acetic acid is in the gaseous state, the molecules are free from any intermolecular forces. so clearly some sort of reaction must have occurred, perhaps dimerzation?

Answer 3

Interesting, apparently in solid and gas phase acetic acid tends to dimerize, but in liquid phase it occurs less often if there are hydrogen bonding solvents. I didn't really read much past this section "Structure" https://en.wikipedia.org/wiki/Acetic_acid#Structure

They also have a nice picture of what he dimer looks like: https://upload.wikimedia.org/wikipedia/commons/b/be/Acetic_Acid_Hydrogenbridge_V.1.svg

Pretty interesting, also good idea on the dimer thing.

Answer 4

Thank you for clarifying @Woodward it seemed strange at first