Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Martin on 18/05/2010 11:30:02

Title: Why is a mole of Hg bigger than a mole of S?
Post by: Martin on 18/05/2010 11:30:02

Martin  asked the Naked Scientists:
   
Hi.  I found your website after a google search.

Can you think of any reason why a mole of mercury (Hg) would occupy significantly less volume than a mole of sulphur (S)?  

Sulphur has a much smaller atomic radius - and mercury is even a liquid at room temp, which one would think would be an added benefit - but no - seems like a mole of solid sulphur occupies about 5x as much volume.  

What's going on here?

Thanks and hope to hear back,

M

What do you think?

Title: Why is a mole of Hg bigger than a mole of S?
Post by: lightarrow on 18/05/2010 12:40:48

Because the Hg atom is heavier...

Title: Why is a mole of Hg bigger than a mole of S?
Post by: chemrbhs on 26/05/2010 02:26:52

I would have to disagree with previous explanation, though it is true that Hg is heavier (atomic mass) than S, I don't think that answers the question, which only appears to be a density problem...
Actually I don't thing this really is an effect of density g/ml, but of a property I don't really have a good name for, atoms/ml.
I think the difference in volume is due to the arrangement of the atoms relative to each other, not to the difference in atomic masses. Evidenced by, the imagination experiment of arranging the atoms of Hg in the same crystalline structure as S. I believe then the larger atomic radii of the Hg atoms would make the same number (1 mole) of atoms of Hg take up more space (volume) than 1 mole of S.

Title: Why is a mole of Hg bigger than a mole of S?
Post by: Bored chemist on 26/05/2010 19:11:52

1 mole of Hg is 200.6 grammes is 14.8 ml.

1 mole of sulphur is 32 grammes is 16 ml

The sulphur atoms are smaller, but they are stuck together in rings in the solid state- that means there are gaps in the middles of the rings and those gaps also take up volume.

Title: Why is a mole of Hg bigger than a mole of S?
Post by: evawanling on 03/06/2010 02:53:04

1 mole of Hg is 200.6 grammes is 14.8 ml.

1 mole of sulphur is 32 grammes is 16 ml

Title: Why is a mole of Hg bigger than a mole of S?
Post by: lightarrow on 03/06/2010 18:08:54

Quote from: chemrbhs on 26/05/2010 02:26:52

I would have to disagree with previous explanation, though it is true that Hg is heavier (atomic mass) than S, I don't think that answers the question, which only appears to be a density problem...
Actually I don't thing this really is an effect of density g/ml, but of a property I don't really have a good name for, atoms/ml.
I think the difference in volume is due to the arrangement of the atoms relative to each other, not to the difference in atomic masses. Evidenced by, the imagination experiment of arranging the atoms of Hg in the same crystalline structure as S. I believe then the larger atomic radii of the Hg atoms would make the same number (1 mole) of atoms of Hg take up more space (volume) than 1 mole of S.

Sorry, i misunderstood the question. You are right.