Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: agBr on September 09, 2018, 03:21:42 AM
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Hello everyone.
I've been trying to find the dissociation constant of borax and sodium metaborate, unsuccessfuly.
I think that if a conjugate K is known, then we can know the K (by just replacing ka by kb or viceversa), but I don't know the conjugates neither.
Maybe I can dissolve some different quantities in pure water, then use kb=[B+][OH-]/[BOH]
For example, for an unkown pkB 3.67, if I measured:
molar pH
0.0001 9.87
0.001 10.56
0.01 11.13
0.1 11.65
Then I could see the expected logarithmic relation to concentration, and estimate kb.
I was looking for a published data, as my pH meter is not high quality, and I'm not very experienced.
It seems strange to me though, as borax is such a common chemical, very much used.
Any recommendation?
Thanks!
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Did you see this
Using Ksp for the Dissolution of Borax in Water to Determine: ∆G°, ∆H° and ∆S°
https://www.scribd.com/doc/227420851/Using-Ksp-for-the-Dissolution-of-Borax-in-Water-to-Determine-G-H-and-S (https://www.scribd.com/doc/227420851/Using-Ksp-for-the-Dissolution-of-Borax-in-Water-to-Determine-G-H-and-S)
Are you doing this at home or in school?
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This is tricky, as there is no single dissociation reaction, rather a complex set of equilibria.
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billnotgatez, at home; no special equipment.
Borek, that might explain why I couldn't find a simple answer.
I was looking for it, to be able to predict (approx) the pH of a solution as a first guess, then fine tune it experimentally.