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### Solids and liquids in K

Posted: Wed Jan 16, 2019 5:01 pm
I know that you don't include solids and liquids into the equation when calculating the equilibrium constant but could someone please explain to me why that is? Thanks friends

### Re: Solids and liquids in K

Posted: Wed Jan 16, 2019 5:05 pm
Since there is excess water its concentration changes slightly and isn't taken into account since it's the solvent.

### Re: Solids and liquids in K

Posted: Wed Jan 16, 2019 5:07 pm
Solids aren't included because they don't have a concentration. Liquids aren't included because they are usually solvents and don't change much in concentration throughout the reaction. Liquids would just show up on both sides of the equation and cancel each other out.

### Re: Solids and liquids in K

Posted: Wed Jan 16, 2019 5:08 pm
Solids and liquids are not included because they do not affect the reaction amount at equilibrium. Solids remain as solids, so their concentration will not change. Also, we assume that there is a large excess of solvent in the reaction, so liquids will remain at the end of the reaction (cancel out in the equilibrium expression).

### Re: Solids and liquids in K

Posted: Wed Jan 16, 2019 5:09 pm
You don't include liquids in your equilibrium expressions because they occur in such large amounts that they are considered the solvents of the chemical reaction. Any reaction that occurs using a liquid will not provide a large enough change to that liquids concentration so as to require us to include it in the equilibrium expression. As for solids, they are not included in the equilibrium expression because the completely ionize in solution, acting as spectator ions. These spectator ions are present on both the reactant and product side of the chemical equation, so they cancel out in the equilibrium expressions.

### Re: Solids and liquids in K

Posted: Wed Jan 16, 2019 5:14 pm
Saman Andalib 1H wrote:You don't include liquids in your equilibrium expressions because they occur in such large amounts that they are considered the solvents of the chemical reaction. Any reaction that occurs using a liquid will not provide a large enough change to that liquids concentration so as to require us to include it in the equilibrium expression. As for solids, they are not included in the equilibrium expression because the completely ionize in solution, acting as spectator ions. These spectator ions are present on both the reactant and product side of the chemical equation, so they cancel out in the equilibrium expressions.

So would it be correct to say that if any liquid or any solid is present on both the reactant and product side of the chemical equation, we do not have to consider them in the equilibrium constant expressions?

### Re: Solids and liquids in K

Posted: Thu Jan 17, 2019 8:12 pm
Miya Lopez 1I wrote:
Saman Andalib 1H wrote:You don't include liquids in your equilibrium expressions because they occur in such large amounts that they are considered the solvents of the chemical reaction. Any reaction that occurs using a liquid will not provide a large enough change to that liquids concentration so as to require us to include it in the equilibrium expression. As for solids, they are not included in the equilibrium expression because the completely ionize in solution, acting as spectator ions. These spectator ions are present on both the reactant and product side of the chemical equation, so they cancel out in the equilibrium expressions.

So would it be correct to say that if any liquid or any solid is present on both the reactant and product side of the chemical equation, we do not have to consider them in the equilibrium constant expressions?

Yes, you don't include them in the equilibrium constant expression.