Units for K
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 100
- Joined: Sat Aug 17, 2019 12:17 am
-
- Posts: 117
- Joined: Sat Sep 14, 2019 12:17 am
Re: Units for K
Actually, the equilibrium constant K has unit, but to include the unit would make the calculation much more complex (and the numerical value of K would be a little bit different--so little that it would be much more convenient to not include a unit for K. To have K have no unit, we would write molar concentration with units omitted. To make K have unit and thus more exact, we could use a = constant * [X], and the constant is assumed to be 1 for us to omit the unit of K.
-
- Posts: 102
- Joined: Wed Sep 30, 2020 9:36 pm
Re: Units for K
I believe that the units cancel out leaving you with just the ratio of products to reactants.
-
- Posts: 51
- Joined: Wed Nov 18, 2020 12:24 am
Re: Units for K
Asia Yamada 2B wrote:I believe that the units cancel out leaving you with just the ratio of products to reactants.
You are correct, there are no units (only a ratio representing amounts of two things) because they all cancel
-
- Posts: 108
- Joined: Wed Sep 30, 2020 9:50 pm
- Been upvoted: 1 time
Re: Units for K
I think because it's a ratio, it has no units. Not 100% sure if that's the correct explanation but that's what a teacher told me in high school.
-
- Posts: 103
- Joined: Wed Sep 30, 2020 9:50 pm
- Been upvoted: 1 time
Re: Units for K
The units for K cancel so there is actually no units. It merely tells us the ratio of products and reactants relative to one another.
-
- Posts: 101
- Joined: Wed Sep 30, 2020 10:03 pm
Re: Units for K
K essentially tells us the ratio of the products and reactants, so the units cancel out.
-
- Posts: 108
- Joined: Wed Sep 30, 2020 10:11 pm
Re: Units for K
In the end, the units cancel out with the ratio which is why K is considered unitless.
-
- Posts: 106
- Joined: Wed Sep 30, 2020 9:59 pm
- Been upvoted: 2 times
Re: Units for K
I don’t think the units can cancel out all the time.
If A(aq) + B(aq) → 2C(aq) + D(aq)
Kc = [C]2 [D] / ([A] [B])
Because there is a square, one unit of [C] would not cancel out, and the unit of Kc should be the unit of [C].
If A(aq) + B(aq) → 2C(aq) + D(aq)
Kc = [C]2 [D] / ([A] [B])
Because there is a square, one unit of [C] would not cancel out, and the unit of Kc should be the unit of [C].
-
- Posts: 51
- Joined: Wed Nov 18, 2020 12:30 am
Re: Units for K
I'd like to second Isabel's response that since K is a ratio, there are no units. I think that's the simplest way of thinking about it, and as far as I know, that's also the most we need to understand, but if you're looking for a further explanation, you can try looking it up.
-
- Posts: 101
- Joined: Wed Sep 30, 2020 10:01 pm
- Been upvoted: 1 time
Re: Units for K
When calculating K, the units of the numerator and denominator cancel, so there are no units associated with K. In this case, K just represents the ratio of products to reactants at equilibrium.
-
- Posts: 101
- Joined: Wed Sep 30, 2020 10:01 pm
- Been upvoted: 1 time
Re: Units for K
When calculating K, the units of the numerator and denominator cancel, so there are no units associated with K. In this case, K just represents the ratio of products to reactants at equilibrium.
-
- Posts: 108
- Joined: Wed Sep 30, 2020 9:40 pm
-
- Posts: 62
- Joined: Tue Nov 17, 2020 12:20 am
Re: Units for K
Since K is just a ratio (of products to reactants), there are not units since they cancel.
-
- Posts: 104
- Joined: Wed Sep 30, 2020 10:03 pm
Re: Units for K
K is a ratio (and a constant overall), so it will not have units!! Also, all the units of concentration or pressure will be cancelled out when you solve for K
-
- Posts: 102
- Joined: Wed Sep 30, 2020 10:06 pm
- Been upvoted: 2 times
-
- Posts: 110
- Joined: Wed Sep 30, 2020 9:59 pm
-
- Posts: 120
- Joined: Wed Sep 30, 2020 9:50 pm
Re: Units for K
Since K is a ratio, when you solve for K all the units cancel out so in the end K is left unitless.
-
- Posts: 2
- Joined: Wed Sep 30, 2020 9:41 pm
Re: Units for K
Isabel_Eslabon_2G wrote:I think because it's a ratio, it has no units. Not 100% sure if that's the correct explanation but that's what a teacher told me in high school.
Yeah because it's just a ratio units aren't applicable
-
- Posts: 46
- Joined: Wed Nov 18, 2020 12:27 am
Re: Units for K
Since its a ratio, the units should cancel out but honestly I actually somewhat doubt that explanation. Someone else mentioned this as well but when if you square one of the substances because they have a coefficient naturally the units should be squared as well. If the reactants aren't squared then this wouldn't cancel out properly. The best explanation that I have is that the equilibrium constant is found arbitrarily without stoichiometry so its not given units due to its inherit definition as a ratio.
-
- Posts: 105
- Joined: Sat Oct 03, 2020 12:15 am
-
- Posts: 102
- Joined: Wed Sep 30, 2020 10:04 pm
Re: Units for K
Since K is a ratio, the units usually cancel our at the end, that's why they're no units with the final answer.
-
- Posts: 101
- Joined: Wed Nov 13, 2019 12:19 am
Re: Units for K
I believe that since K is a ratio, the units cancel out and you are just left with the value!
-
- Posts: 80
- Joined: Wed Sep 30, 2020 9:52 pm
Re: Units for K
yes K is typically a ratio but sometimes pressures can be added to an equation in a similar manner where the pressures are to the power of thier coefficient and where the whole fraction is not equal to 1.
-
- Posts: 51
- Joined: Tue Nov 05, 2019 12:18 am
Re: Units for K
There are no units for K because it cancels out. K is a ratio, so you are just left with a value.
-
- Posts: 100
- Joined: Wed Sep 30, 2020 9:47 pm
Re: Units for K
Great question! There are no units, because they all cancel out. If you were to make a fraction of products over reactants with the respective units (molarity)...you would find that they all cancel! This is because K is a ratio of products and reactions at equilibrium.
-
- Posts: 116
- Joined: Wed Sep 30, 2020 9:39 pm
-
- Posts: 111
- Joined: Wed Sep 30, 2020 10:01 pm
Re: Units for K
Since K is just informing us of a ratio(of Products to Reatants) the units would cancel and that's why K doesn't contain any units.
Who is online
Users browsing this forum: No registered users and 3 guests