How to prepare 1M H2O2 using 30% hydrogen peroxide?
(by pow.joshi from gmail.com)
Wed Feb 6 13:09:45 EST 2008
On 05/02/2008, DK <dk from no.email.thankstospam.net> wrote:
> In article <
> 4f8737e1-bbe4-4542-8c1e-e98c7cddab5a from e6g2000prf.googlegroups.com>, WS <
> novalidaddress from nurfuerspam.de> wrote:
> >Dear Lao,
> >that's the real issue. All your assumptions may be true.
> >IMHO is is *absolutely* necessary to specify m/v (mass/volume), m/m or
> >v/v. It even makes a difference if you (in this case rather
> >hypothetically as solid H2O2 does not exist [at least for a long
> >time]) mix 300 ml of H2O2 and 700ml of water, put 300 ml H2O2 in a
> >beaker and add water up to 1liter or vice versa.
> Industrial % concentrations tend to be m/m. This is clearly
> the case, for example, with concentrated HCl (~ 37% ~ 12M)
> or concentrated H3PO4 (85% = 15.2M).
> MSDS for 30% H2O2 says "balance water", suggesting
> that indeed we are talking about 300 g + 700 g water.
> In which case precise molarity calculattion become
> troublesome even knowing density of 100% H2O2
> because water solutions can change volume
> appreciably (e.g. 500 ml ethanol + 500 ml H2O
> will result in less than 1000 ml solution).
> Not that any of that matters in the experiment in
> question! Assuming no volume change and m/m
> for 30% and density off 199% of 1.4 g/ml from
> Wikipedia, we get 22-28% error depending on the
> direction. With the "1 M" being clearly an arbitrary
> round number, I wouln't worry about potential
> 25% error as long as the way the solution is prepared
> is clearly stated.
yes, that is true.... H2O2 would be w/w.... the MSDS generally does'nt give
the information, however, calling the company would give. Frankly, I did'nt
know that this is true for all industrial preparation..... Thank you Dima.
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