## Solids and liquids [ENDORSED]

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AlyssaYeh_1B
Posts: 100
Joined: Sat Aug 17, 2019 12:16 am

### Solids and liquids

I understand why solids cannot be included in the equilibrium constant, but how come liquids cannot? It's possible to measure the concentration of liquids right?

Jielena_Bragasin2G
Posts: 104
Joined: Sat Aug 24, 2019 12:18 am
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### Re: Solids and liquids

This is because the molar concentration of a pure substance (solid or liquid) does not change in a reaction. Dr. Lavelle also said that there is no such thing as a concentration of a pure solid or a liquid, therefore it is not included in the K expression.

005391550
Posts: 103
Joined: Thu Jul 25, 2019 12:15 am

### Re: Solids and liquids  [ENDORSED]

you can think of liquids as solvents like H2O. molecules of a solvent can technically react but the vast majority of the solvent will stay a solvent which means there is no significant change in concentration. since there is not significant change, including the concentration of liquid would just cancel out because it will stay the same.

Rebekah Alfred 1J
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### Re: Solids and liquids

When trying to understand why liquids and solids are not included in the equilibrium constant, remember that the activity, which Dr. Lavelle discussed when going over equilibrium constants, of any solid or liquid in a reaction is equal to 1.

kausalya_1k
Posts: 50
Joined: Wed Nov 14, 2018 12:23 am

### Re: Solids and liquids

Liquids are considered pure substances, so their concentration wouldn't change in a reaction. Therefore, their activity is equal to 1 (just like solids) which is why we don't include it in the K calculation.

Andres Merlos 2L
Posts: 46
Joined: Wed Sep 18, 2019 12:17 am

### Re: Solids and liquids

Since liquids are considered a pure substance, the molar concentration would not change in a reaction. We do not consider them in the equilibrium constant because of this.

Daria MacAuslan 1H
Posts: 50
Joined: Sat Aug 17, 2019 12:16 am

### Re: Solids and liquids

The activity of pure substances is equal to 1, which means that in a reaction their concentration will not ever change. Because of this, liquids are not included in the calculations.