## Calculating Kc

Suraj Doshi 2G
Posts: 100
Joined: Fri Aug 02, 2019 12:15 am

### Calculating Kc

Why do we not include solids or liquids in the equilibrium concentration calculations?

Kishan Shah 2G
Posts: 132
Joined: Thu Jul 11, 2019 12:15 am

### Re: Calculating Kc

Basically solids and liquids have a constant concentration. There may be very tiny changes in volume of them but its not enough to affect our calculations. The activity of solids and liquids at equilibrium is 1, so therefore it doesn't affect equilibrium concentrations.

stephaniekim2K
Posts: 79
Joined: Fri Aug 09, 2019 12:16 am

### Re: Calculating Kc

Solids and liquids have constant concentrations so they don't change, so there is no need to calculate them.

sarahforman_Dis2I
Posts: 109
Joined: Sat Aug 17, 2019 12:18 am

### Re: Calculating Kc

Suraj Doshi 2G wrote:Why do we not include solids or liquids in the equilibrium concentration calculations?

It is important to note that solvents (eg. liquid water) are not included in the equilibrium expression because only a minimal amount of the solvent is taken away in the reaction. Because of this, we can assume that the solvent concentration is essentially constant and therefore not include it in the equilibrium constant.

Tiffany_Chen 2K
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

### Re: Calculating Kc

Solids and liquids will hold relatively constant volume, thus you can technically "cancel" them out when putting products over reactants to find Kc.

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