### Units for K

Posted:

**Sun Jan 12, 2020 5:35 pm**So we do not use units for K? Can someone explain this to me?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=49&t=56088

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Posted: **Sun Jan 12, 2020 5:35 pm**

So we do not use units for K? Can someone explain this to me?

Posted: **Sun Jan 12, 2020 5:40 pm**

No because K is a constant. We use brackets around equilibrium concentration. The brackets indicate molar concentration so we omit actual units.

Posted: **Sun Jan 12, 2020 5:42 pm**

K is representative of a ratio, products/reactants. It is used to compare rates of reaction and therefore does not have units.

Posted: **Sun Jan 12, 2020 5:49 pm**

Neither K nor Q have units

Posted: **Sun Jan 12, 2020 5:51 pm**

K doesn't have units technically because they all cancel out, and it comes out to be just a number ratio.

Posted: **Sun Jan 12, 2020 5:52 pm**

Equilibrium constants have no units; this is because it is a ratio of similar quantities.

Posted: **Sun Jan 12, 2020 5:56 pm**

K doesn't have units because it is a ratio of molar concentrations.

Posted: **Sun Jan 12, 2020 8:22 pm**

K does not have any units associated with it, since it's just a ratio of different molecules and species.

Posted: **Sun Jan 12, 2020 8:37 pm**

K is a constant because when calculating it all the units cancel out, so there is no unit for it.

Posted: **Sun Jan 12, 2020 10:03 pm**

K is a constant, meaning there are no units used. But, it is a good way to check your work if you end up with units because there should not be any because they should all cancel out.

Posted: **Sun Jan 12, 2020 10:16 pm**

In class, Dr. Lavelle mentioned briefly saying that technically K is the ratio if the activities of the products and reactants, which is unit-less.

Posted: **Sun Jan 12, 2020 10:28 pm**

Since K is a ratio of values with the same units, they cancel out and are not present in the K value. I would still include them in the K expression to show my work though!

Posted: **Sun Jan 12, 2020 10:41 pm**

There is no unit for K, it is a constant for equilibrium. You can prove this because when you solve for K, all the units cancel out.

Posted: **Sun Jan 12, 2020 11:40 pm**

There are no units since K is more so a ratio

Posted: **Sun Jan 12, 2020 11:58 pm**

K has no units because of "activity"; however, activity is really low (close to 1) for the most part, so the equation ratio is simplified to the form that we know. But also, in the ratio, the units in the numerator and denominator will cancel out.

Posted: **Mon Jan 13, 2020 11:34 am**

K has no units but units you plug in matter, so use mol/L not mL or mol.

Posted: **Mon Jan 13, 2020 12:28 pm**

K has no units as hen you do all the calculations, the units cancel out. Furthermore, this is because K is just a constant.

Posted: **Mon Jan 13, 2020 12:29 pm**

K does not have units it is a constant.

Posted: **Mon Jan 13, 2020 1:41 pm**

Since K is a constant it does not have units associated with it!

Posted: **Mon Jan 13, 2020 10:23 pm**

K does not have units. The brackets signify its molarity or concentration of a reactant or product. As Dr. Lavelle discussed in class the true way to explain is via the ratio of the activities of the reactants and product. K is simply giving us the relative information of the rates and which reaction is favored. Activities don't have units and the expression we write assumes the activities are close to 1.

Posted: **Mon Jan 13, 2020 11:29 pm**

K does not have units as it is a constant value of the ratio of concentrations of products to reactants.

Posted: **Tue Jan 14, 2020 9:33 am**

K, a constant, demonstrates the ratio of products and reactants so it does not have units