Glycerol: v/v or w/v?

a.krimer at biosidus.com.ar a.krimer at biosidus.com.ar
Fri Feb 25 08:17:25 EST 2000


Dear Frank:

I think you didn't mix very well. Mixing EtOH and water was an old experiment of
the Physico-Chemistry course in my Faculty of Science.
This was performed to calculate the specific volume of tthe solution. The
importance of that i don't remember, but I remember after mixing 50 ml each one
the final volume was less than 100 ml.
Good luck
Alejandro




"Frank O. Fackelmayer" <Frank.Fackelmayer at uni-konstanz.de> on 02/25/2000
06:55:23 AM

Please respond to Frank.Fackelmayer at uni-konstanz.de

To:   methods at hgmp.mrc.ac.uk
cc:    (bcc: Alejandro Krimer/DESARROLLO/BIOSIDUS/GRUPOSIDUS)
Fax to:
Subject:  Re: Glycerol: v/v or w/v?



Wolfgang Schechinger wrote:

> No. Not obviously. I use w/v. Did you ever try to pipet 100%
> glycerol? For this reason, one always should how the dilution was
> performed.
> In real life, it normally should not matter. What matters more is,
> that there is a difference if you have 50 ml of glycerol and add
> water q.s. 100 ml or if you have 50 ml of water and add glycerol q.s.
> 100 ml. For understanding this phenomenon, mix 50 ml of ethanol
> **and** 50 ml of water in a graded cylinder (the experiment is easier
> to perform with EtOH).
>
>

just did it, just for curiosity.  Adding 50ml water to 50ml EtOH gave
100ml, adding 50ml EtOH to 50ml water also gave 100ml.
What difference should I see? Why?
Frank

PS: I always use v/v for glycerol solutions. w/v is certainly also
correct, although the solution will be less concentrated then. Why not
simply state (v/v) or (w/v) in your protocols to make things clear?








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