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### Calculating K

Posted: Sat Jan 11, 2020 10:00 pm
Why do we not include solids or liquids when calculating K?

### Re: Calculating K

Posted: 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

### Re: Calculating K

Posted: 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.

### Re: Calculating K

Posted: 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.

### Re: Calculating K

Posted: 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.

### Re: Calculating K

Posted: 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.