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### Solids and Liquids in K

Posted: Mon Jan 14, 2019 4:01 pm
I understand that solids and liquids should not be included in the calculation of K values, but could someone explain why this is? Why are they insignificant?

### Re: Solids and Liquids in K

Posted: Mon Jan 14, 2019 4:03 pm
Solids and liquids have no concentration/partial pressures so they can't be included in the expression.

### Re: Solids and Liquids in K

Posted: Mon Jan 14, 2019 4:10 pm
from my understanding it is that you can't really define the concentration of lets a solid block of salt since the entire thing is pure salt, this can also be applied to any other solid. For liquids like water it is because the start and end concentration are so large and similar that it doesn't matter for the concentration. hope this helps a bit

### Re: Solids and Liquids in K

Posted: Mon Jan 14, 2019 5:22 pm
Solids do not have a concentration, it can only be measured by mass and density. Pure liquids take part in very little of the reaction so the outcome of the liquid is quite insignificant. Dr. Lavelle used an analogy in class that explained this concept well: if you have a million dollars and you give one dollar away, you would still say you have a million dollars. Therefore, pure liquids are not included in the equilibrium constant because their ratio is simply 1, which does not affect the k value.

### Re: Solids and Liquids in K

Posted: Mon Jan 14, 2019 5:55 pm
^as mentioned above, pure solids and liquids are not involved in any K expression. HOWEVER, H20 in aqueous or gas form is used in equilibrium expressions (refer to the first 10 problems in Homework in chapter 11)