Why Br2 with Br2 has higher viscosity than HF with HF?

1 Answer
Feb 14, 2017

Answer:

So we assess the viscosities of the liquids #HF# and #Br_2#?

Explanation:

There are dispersion forces between the bromine molecules: the electrons cloud can transiently distort to provide intermolecular interaction. On the other hand, in pure #HF#, the dominant intermolecular force is hydrogen bonding, i.e. #""^(delta+)H-F^(delta-)#.

But the best indicator of intermolecular force is the boiling point. Bromine has a boiling point of #58.8# #""^@C#; for pure #HF#, #19.5# #""^@C#. On this metric, the intermolecular force is greater for bromine. Given the greater intermolecular attraction, we would anticipate that bromine is more viscous than hydrogen fluoride. This is not an experiment I would care to perform. Both substances are highly corrosive, and can cause horrendous burns.