Glycerol: v/v or w/v?

Frank O. Fackelmayer Frank.Fackelmayer at uni-konstanz.de
Fri Feb 25 04:55:23 EST 2000


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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