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Reason for not including water

Posted: Tue Dec 05, 2017 4:59 pm
by Gurvardaan Bal1L
Do we not include water in the acidity/basicity constants because it is a pure liquid or because it is in excess? I heard both from different people and wanted to know which is correct or if both are correct.

Re: Reason for not including water

Posted: Tue Dec 05, 2017 5:18 pm
by kaushalrao2H
for K (acid/base) constants, we only use concentrations of aqueous or gaseous substances, and leave out pure substances (solid and liquid).

Re: Reason for not including water

Posted: Wed Dec 06, 2017 8:33 am
by Nha Dang 2I
Yeah, you don't include water because it is a liquid. Liquids and solids aren't included in the constants because they don't affect the reactant amount at equilibrium.

Re: Reason for not including water

Posted: Wed Dec 06, 2017 9:48 am
by JamesAntonios 1E
Both your reasons that you stated are equally correct. Remember though than in Le Chatelier's Principle, the concentration of everything can be affected by the addition or subtraction of water.

Re: Reason for not including water

Posted: Thu Dec 07, 2017 1:53 am
by AnuPanneerselvam1H
Since water is the solvent, it's concentration will barely be affected. Therefore it is not included in the equilibrium ratio.

Re: Reason for not including water

Posted: Fri Dec 08, 2017 1:56 pm
by Jorge Gomez3F
We do not include water because it present in such a great quantity that the reaction will not change how much there is. Also water is a pure liquid and a solvent therefore it can technically be both.

Re: Reason for not including water

Posted: Fri Dec 08, 2017 4:22 pm
by Matt_Fontila_2L_Chem14B
Water is the solvent in which the reaction occurs. It's not included in the K expression.