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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Lumo on July 13, 2012, 05:35:07 PM

Title: Is 10N sodium hydroxide the same as 10M
Post by: Lumo on July 13, 2012, 05:35:07 PM

Hello,

I need to make 10ml of 2M NaOH. The stock solution is 10N and I have read somewhere that for NaOH M = N and therefore I should just treat it as 10M.

So to make 10Ml I take 2ml sodium hydroxide and add it to 8 ml ddh20.

Is this correct? Any tips much appreciated!

Thanks

Title: Re: Is 10N sodium hydroxide the same as 10M
Post by: Arkcon on July 13, 2012, 05:55:42 PM

Yep.  Normality (N) for NaOH is the same as Molarity (M).  Make sure you look up the definitions of those two concentration measurements so you're ready for the cases when that is not true.  For H₂SO₄, for example.

Title: Re: Is 10N sodium hydroxide the same as 10M
Post by: Lumo on July 16, 2012, 11:04:31 AM

Quote from: Arkcon on July 13, 2012, 05:55:42 PM

Yep.  Normality (N) for NaOH is the same as Molarity (M).  Make sure you look up the definitions of those two concentration measurements so you're ready for the cases when that is not true.  For H₂SO₄, for example.

Great! Many thanks. Yes, I realized it was often different which is why I was surprised to find it the same for NaOH

Title: Re: Is 10N sodium hydroxide the same as 10M
Post by: Jasim on July 16, 2012, 03:35:30 PM

With respect to acid-base chemistry, normality is a measure of the concentration of H⁺ or OH^- (or equivalent) that can be produced by a particular acid or base. For most it is equal to the molarity, which is simply the concentration. A good example of when it's not equivalent is with diprotic and triprotic acids.

For instance with sulfuric acid (H₂SO4), which is diprotic, a 1M solution would be 2N. In this case 1M = 2N. That is because a single molecule of (H₂SO4) can produce two H⁺.

A single molecule of NaOH produces a single OH^- anion, so for NaOH, M = N always.