## Equilibrium constants

Emma McGinnis 1G
Posts: 12
Joined: Fri Sep 25, 2015 3:00 am

### Equilibrium constants

Just a conceptual question, why are solids not included when calculating an equilibrium constant?

Miah Khan 3L
Posts: 13
Joined: Fri Sep 25, 2015 3:00 am

### Re: Equilibrium constants

This is because they do not affect the reactant amounts at equilibrium in the reaction, so they are thrown out and kept at 1.

Shaye Busse 3B
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Equilibrium constants

Solids are not factored into equilibrium constant calculations because of the nature of how the equilibrium constant is calculated and the nature of solids themselves. To calculate the equilibrium constant, the concentration of products is divided by the concentration of reactants. Solids themselves can not have concentrations because a concentration is moles of solute per liter of solution. There is no solution for a solid, meaning there can be no concentration of solids. Due to this, solids are not factored into the equilibrium constant calculation.

Posts: 6
Joined: Wed Sep 30, 2015 3:00 am

### Re: Equilibrium constants

If your quadratic equation, when finding the concentration of something, results in 2 positive positive numbers, do you use both to calculate the composition of the equilibrium mixture?

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

### Re: Equilibrium constants

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, solids can be excluded from the equilibrium constant.