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Calculating K when there is multiple phases

Posted: Thu Jan 09, 2020 1:19 pm
by Phuong Tran 1G
What do you do when the equilibrium equation includes both aqueous and gas phases? Do you solve for each independently and somehow add them or do you convert?

Re: Calculating K when there is multiple phases

Posted: Thu Jan 09, 2020 1:35 pm
by Alice Ma 2K
You would have to convert the gaseous species into concentration using the Ideal Gas Law and find Kc. There is no way to find Kp because the aqueous species have no partial pressure.

Re: Calculating K when there is multiple phases

Posted: Thu Jan 09, 2020 1:47 pm
by Andrew Liang 1I
I think in that case we would need to convert the gas to molar concentration using the equation: concentration= P/RT.

Re: Calculating K when there is multiple phases

Posted: Thu Jan 09, 2020 2:21 pm
by kim 2I
When calculating K, all the components should be in the same "form/units." Therefore, the concentration of the gas would have to be calculated using the Ideal Gas Law of PV=nRT (divide by V on both sides, moles (n) over V = concentration, therefore, conc=P/RT). Finally the Kc can be calculated: Kc=[products]/[reactants].

Re: Calculating K when there is multiple phases

Posted: Fri Jan 10, 2020 12:07 am
by Amy Xiao 1I
Thank you for clarifying why aqueous solutions cannot have partial pressure; I was under the impression that you could convert either to partial pressure or concentration for each of them.