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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Fry on October 20, 2007, 12:37:46 AM

Title: "N" - notation ... ie. 3.0 N HCl
Post by: Fry on October 20, 2007, 12:37:46 AM

I was taught that N was a manufacturer guarantee of how pure the substance is, that 3.0 N meant that the substance was 99.9 percent pure etc.

Is it just the same general idea for 0.1 N and 3.5N type substances? so it would be 0.9 percent and 31.5 percent respectively? Am I missing anything?

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: Yggdrasil on October 20, 2007, 12:43:03 AM

N stands for normality which is a measure of the number of "equivalents" per liter.  What is an equivalent you ask?  Basically, one equivalent is one reactive unit.  In the case of acids, one the reactive unit is one acidic proton.  So, a 3M solution of HCl will contain 3 moles of acidic protons per liter giving a normality of 3N.  However, a 3M solution of H₂SO₄ has 6 moles of acidic protons per liter, giving a normality of 6N.

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: Fry on October 20, 2007, 04:53:42 AM

Thanks!

Ah, so it IS different in analytical chemistry.

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: agrobert on October 21, 2007, 04:02:49 AM

The N for normality is standard in all divisions of chemistry.

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: Fry on October 21, 2007, 12:55:32 PM

So what was my analytical professor babbling on about?

He claimed that a number followed by 'N' meant how many nines there are...  ???

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: Yggdrasil on October 21, 2007, 01:11:21 PM

I've never heard that definition before.

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: Borek on October 21, 2007, 01:30:03 PM

I think I have heard about something similar, but it was used to describe substance purity. Can't remember details right now.

Title: Re: "N" - notation ... ie. 3.0 N HCl
Post by: sjb on October 22, 2007, 06:31:26 AM

It may not be an N, rather a nines notation, or similar.

So "5 9's" pure would represent 99.999% etc

??

S