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Solid and Liquid

Posted: Mon Jan 13, 2020 12:33 pm
by Junwei Sun 4I
Why is it that when we write the expression for K we don't include solid and liquid? Is it because their concentration does not change or is it that the change is insignificant? Also for solid and liquid do we always write them as 1 in the equilibrium expression?

Re: Solid and Liquid

Posted: Mon Jan 13, 2020 1:22 pm
by Hannah Romeo 1J
Solids and liquids are not included in the K expression as they do not change their concentrations in a reaction as they are pure substances. Essentially, their value is 1 resulting in the K expression only including aqueous solutions.

Re: Solid and Liquid

Posted: Mon Jan 13, 2020 2:12 pm
by Alex Tchekanov Dis 2k
You are correct that that the concentration change is insignificant. You definitely need some of the solid and liquid to make the product, but the concentration difference is negligible.

Re: Solid and Liquid

Posted: Mon Jan 13, 2020 2:14 pm
by Kishan Shah 2G
Yes, the concentration change of solids and liquids is insignificant. If you think about it, if they do not affect the concentrations of reactants/products, then they serve no purpose in the equilibrium constant.

Re: Solid and Liquid

Posted: Mon Jan 13, 2020 2:42 pm
by Mariah
Hannah Romeo 1J wrote:Solids and liquids are not included in the K expression as they do not change their concentrations in a reaction as they are pure substances. Essentially, their value is 1 resulting in the K expression only including aqueous solutions.


As well as gases!!

Re: Solid and Liquid

Posted: Mon Jan 13, 2020 4:07 pm
by VLi_2B
Mariah wrote:
Hannah Romeo 1J wrote:Solids and liquids are not included in the K expression as they do not change their concentrations in a reaction as they are pure substances. Essentially, their value is 1 resulting in the K expression only including aqueous solutions.


As well as gases!!


Wait, I thought gases were included in the K expression... Can someone reexplain this to me?