[Catauro]

Hey everyone.  Long time reader, first time poster here.  I was just browsing and I came across this page referring to number density, and defining this as n/V, which I would assume to be "molar quantity divided by volume."  However, this formula, n/V appears to be the exact same as the formula for molar concentration, which is c = n/V.  

Am I misinterpreting the variables/definition at all?  Any help would be appreciated.  Here's the site if you want to check it out: http://scholar.chem.nyu.edu/0651/notes/pchem/node25.html     approximately halfway down the page.  Thanks a lot.

[Mitch]

One looks like its used for liquids and the other for gases.

[Byrne]

One looks like its used for liquids and the other for gases.

But doesn't n/V define concentration for both gases and liquids?  I think he wants to know what the difference is between number density (n/V) and molar concentration (n/V), if there is any.  I can't say because I don't know.

[Mitch]

Right. This might be a case of gas chemists and liquid chemists naming the same concept two separate ways.

[mike]

Isn't n in this case the number of molecules?

[Mitch]

the number of moles of gas n

http://scholar.chem.nyu.edu/0651/notes/pchem/node25.html

[mike]

Yes that's right, so they are the same, right?

n is the number of molecules (in moles) so density and concentration are really the same thing, how much of something in a certain space.

[Mitch]

so density and concentration are really the same thing, how much of something in a certain space.

Aside from the former being an intensice and the ladder an extensive quantity, I suppose they are related.

[incredible]

Molar density is the property of the single component.....like moles of component "A"/volume occupied by component "A".
while, concentration uses the total volume of mixture or solution instead of that component..

[Borek]

Ah, nothing like necroposting in a 5 years old thread.

Molar density is the property of the single component.....like moles of component "A"/volume occupied by component "A".
while, concentration uses the total volume of mixture or solution instead of that component..

They will be identical for pure substances.