Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: wytw on October 23, 2016, 04:59:07 AM
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Hello everyone,
For the oxygen reduction in aqueous solution :
O2(aq) + 2H+(aq) +2e ::equil:: H2O2(aq)
(the correct state for H2O2 is liquid or aqueous ?)
My question is how to write the nernst equation ? Because in my case it is relevant to use the concentration of oxygen and not the partial pressure as in standard conditions, so how can I express the formal potential ? I didn't find any values for it...
Thanks for your help ! :)
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(the correct state for H2O2 is liquid or aqueous ?)
Why the doubt?
My question is how to write the nernst equation ? Because in my case it is relevant to use the concentration of oxygen and not the partial pressure as in standard conditions, so how can I express the formal potential ?
No idea what you are doing that excludes use of the partial pressure, but do you know Henry's law?
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Thanks for replying !
Its about electrochemical experiments so the oxygen is dissolved in water and not considered as gaseous.
And yes I know Henry's law, so I know the concentrations, my question was more about writing the "correct" form of the Nernst equation in this case, owning this.
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Gaseous oxygen is always in equilibrium with the dissolved one, so both versions - using concentration and the partial pressure - are correct and equivalent.
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In resume ?
E=E0 - RT/2F ln([H2O2]/(cO2/HO2*[H+]2)
Where H is the Henry constant of oxygen expressed in term of molarity.
Thanks !