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Solids and Liquids

Posted: Wed Jan 08, 2020 2:02 pm
by briannam_1F
Can someone further explain why we leave out solids and liquids when calculating K?

Re: Solids and Liquids

Posted: Wed Jan 08, 2020 2:05 pm
by sarahsalama2E
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.

Re: Solids and Liquids

Posted: Wed Jan 08, 2020 6:08 pm
by Brianna Becerra 1B
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.

Re: Solids and Liquids

Posted: Wed Jan 08, 2020 6:10 pm
by AlyshaP_2B
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.

Re: Solids and Liquids

Posted: Wed Jan 08, 2020 7:31 pm
by Harry Zhang 1B
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.

Re: Solids and Liquids

Posted: Wed Jan 08, 2020 8:35 pm
by SarahCoufal_1k
You omit them because there is usually so much excess that the actual amount then used is insignificant in terms of molar concentration.

Re: Solids and Liquids

Posted: Thu Jan 09, 2020 12:25 pm
by 005321227
The reason solids are not used in equilibrium reactions is because their concentrations stay constant throughout the reaction

Re: Solids and Liquids

Posted: Thu Jan 09, 2020 12:27 pm
by Max Madrzyk Dis 4G
Solids and liquids are not included because their concentrations stay the same throughout the reaction so there is no need to calculate the change.