Calculating K

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Drew Myers 4G
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

Calculating K

Postby Drew Myers 4G » Sat Jan 11, 2020 10:00 pm

Why do we not include solids or liquids when calculating K?

Sofia Ban
Posts: 80
Joined: Fri Sep 28, 2018 12:25 am

Re: Calculating K

Postby Sofia Ban » Sat Jan 11, 2020 10:14 pm

we don't include those two states because molar concentration of a pure substance doesn't change in a reaction

Jonathan Gong 2H
Posts: 105
Joined: Sat Jul 20, 2019 12:16 am

Re: Calculating K

Postby Jonathan Gong 2H » Sat Jan 11, 2020 10:15 pm

Solids and liquids are excluded from the equilibrium expression because their concentrations stay constant throughout the reaction. In other words, they have no impact on reactant concentrations at equilibrium. Hope this helps.

Cindy Adiwidjaja 1B
Posts: 100
Joined: Sat Jul 20, 2019 12:15 am

Re: Calculating K

Postby Cindy Adiwidjaja 1B » Sat Jan 11, 2020 10:36 pm

We do not include solids and liquids when we calculate K because they stay constant and will ultimately have no effect on K. If you did want to include it, then you would still be essentially adding it to the top (products) and bottom (reactants) and they would still divide out to be 1.

Posts: 100
Joined: Thu Jul 11, 2019 12:17 am

Re: Calculating K

Postby MaggieHan1L » Sun Jan 12, 2020 12:19 am

If you included it since the concentration doesn't change, the liquid and solid would just cancel out.

Eva Zhao 4I
Posts: 101
Joined: Sun Sep 29, 2019 12:16 am

Re: Calculating K

Postby Eva Zhao 4I » Mon Jan 13, 2020 8:29 am

Liquids and solids have an essentially constant concentration because they are practically incompressible. As a result, it takes enormous pressure to cause even a tiny reduction in volume. As such liquids and solids can be excluded from the equilibrium constant.

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