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Topic: calculation of concentration  (Read 5910 times)

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Offline missaturn

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calculation of concentration
« on: February 22, 2008, 03:02:57 AM »
I need some guidance for the calculation of concentration of chemicals which I plan to dilute as stock solution. i have three chemicals which provide different information, . How to calculate the concentration of the chemicals so  i can prepare a stock solution from them? Below are the information provided:

a)nitrosomorpholine: 1ml, FW 116.12

b)n-nitrosodiethylamine: 10ml, d=0.950, MW: 102.14

c)nitrosopyrrolidine: 99%, FW=100.12, d=1.094

Thanks.

Offline ARGOS++

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Re: calculation of concentration
« Reply #1 on: February 22, 2008, 03:29:40 AM »

Dear Missaturn;

You don’t believe you have forgotten some information about your Problem?

Or should it mean that all is mixed together, but in this case what’s the volume/mass of Nitrosopyrrolidine?

I think in this form nobody can solve anything, as nobody (except you) can spend all the missing information.

Please check your Problem once again.

Good Luck!
                    ARGOS++

Offline JGK

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Re: calculation of concentration
« Reply #2 on: February 22, 2008, 08:34:31 AM »
Argos is correct, how can anybody tell you how to prepare a stock solution when you have not provided the necessary infomation on the concentrations or relative ratios of the individual components  which are required.

I'm up for the challenge of helping out, but I'm not telepathic (just expected to be  ::))
Experience is something you don't get until just after you need it.

Offline Arkcon

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Re: calculation of concentration
« Reply #3 on: February 22, 2008, 09:24:36 AM »
A stock solution is a concentrated solution that you prepare for later dilution.  There are a number of reasons for this.  A substance may not be very soluble in water, you'd need say a 0.01 M solution, but you'd never be sure that tiny amount dissolved.  You'd prepare a 0.1 M solution in alcohol or other solvent, then dilute in water.

Even if a substance is somewhat soluble, you wouldn't be sure a small amount was well mixed in a large volume.  So you'd prepare a somewhat more concentrated stock solution, then dilute for working solution.

Like everyone else said, your protocol should tell you what the stock solution concentration should be, unless they've told you elsewhere, or expect you to ask some local expert, check the flasks in the lab for what's written on them, check published literature, etc.

We can't just suggest 0.1 M or 1 M for a stock solution, because don't know how soluble your solids are, how stable they are in concentrated or dilute solution, or what your application is.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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