## Solids and Liquids

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briannam_1F
Posts: 35
Joined: Wed Sep 18, 2019 12:18 am

### Solids and Liquids

Can someone further explain why we leave out solids and liquids when calculating K?

sarahsalama2E
Posts: 164
Joined: Fri Aug 30, 2019 12:16 am

### Re: Solids and Liquids

Solids and Liquids are left out when writing the equilibrium expressions because essentially their concentrations stay the same during the reaction. Also, pure substances such as pure liquids and pure solids are left out when writing equilibrium expressions because their concentrations can't change. An example of a pure substance, in particular, a pure liquid, is water.

Brianna Becerra 1B
Posts: 117
Joined: Fri Aug 02, 2019 12:16 am

### Re: Solids and Liquids

Liquids are omitted when calculating the equilibrium constant because when there is a solvent, the concentration does not change since there is such a large excess making it insignificant to the calculation. Solids are not used because they do not have molar concentrations.

AlyshaP_2B
Posts: 112
Joined: Wed Sep 18, 2019 12:19 am

### Re: Solids and Liquids

During lecture, Lavelle said solids are excluded because they don't have molar concentrations, and liquids are excluded because the solvent concentration stays the same.

Harry Zhang 1B
Posts: 101
Joined: Sat Sep 14, 2019 12:16 am

### Re: Solids and Liquids

They are not included because they are not dissolved and hence their concentration is constant or cannot be calculated. Even if you put some more pure solid or some more pure liquid into the solution, you are just increasing the amount of such solid or liquid but their concentration does not change.

SarahCoufal_1k
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

### Re: Solids and Liquids

You omit them because there is usually so much excess that the actual amount then used is insignificant in terms of molar concentration.

005321227
Posts: 90
Joined: Sat Sep 07, 2019 12:15 am

### Re: Solids and Liquids

The reason solids are not used in equilibrium reactions is because their concentrations stay constant throughout the reaction