Equilibrium constant for water

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Haley Dveirin 1E
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Joined: Sat Jul 20, 2019 12:17 am

Equilibrium constant for water

Postby Haley Dveirin 1E » Mon Jan 13, 2020 1:56 pm

when writing the equilibrium constant for water, why do we omit [H20] from the expression?

Posts: 143
Joined: Fri Aug 30, 2019 12:16 am

Re: Equilibrium constant for water

Postby sarahsalama2E » Mon Jan 13, 2020 2:02 pm

you omit the h20 from the expression because its liquid and also the concentration unchanged.

Alex Tchekanov Dis 2k
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Joined: Sat Aug 24, 2019 12:16 am

Re: Equilibrium constant for water

Postby Alex Tchekanov Dis 2k » Mon Jan 13, 2020 2:06 pm

You also do this because the activity of water is said to be one and thus when you multiply by one, it does not change the K value

Brian Tangsombatvisit 1C
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Joined: Sat Aug 17, 2019 12:15 am

Re: Equilibrium constant for water

Postby Brian Tangsombatvisit 1C » Mon Jan 13, 2020 2:21 pm

H2O is a solvent, and we omit all solvents from the K expression since they will be in large excess compared to the concentrations of the other aqueous reactants and products. Its concentration will not change after equilibrium is met, so it is insignificant and can be omitted from the K expression.

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