Units for K and Q [ENDORSED]

MCracchiolo 1C
Posts: 55
Joined: Sat Jul 22, 2017 3:00 am

Units for K and Q

Even though K and Q do not have units, do the values you use to calculate K and Q need to be in specific units, say, (mol*L^-1)?

Posts: 21
Joined: Fri Sep 29, 2017 7:04 am

Re: Units for K and Q

For Kc and when comparing it with Q, the values to calculate must be in mol/L since Kc is the equilibrium constant based off of concentration.

MCracchiolo 1C
Posts: 55
Joined: Sat Jul 22, 2017 3:00 am

Re: Units for K and Q

What does K(p) have to be in terms of? bar?

Minie 1G
Posts: 63
Joined: Fri Sep 29, 2017 7:04 am

Re: Units for K and Q

You just have to use the same constant for all your calculations. Since the units eventually cancel out to render K unitless, it doesn't really matter as long as it's all the same (so don't use atm for one molecule and bar for another, but if you use atm for all then all the atms cancel anyways).

Similarly for Kc, if you wanted to be weird and do everything in mol/mL instead of the standard mol/L you'd get the same answer for Kc since all your values are modified by the same amount. (think like 1/2 = 0.5 and 0.001/0.002 = still 0.5).

camrynpatterson3C
Posts: 44
Joined: Fri Sep 29, 2017 7:07 am

Re: Units for K and Q

Adding on to this, for pressure specifically, are bars and atms interchangeable? If not, what is the conversion between them?

Lauren Seidl 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

Re: Units for K and Q  [ENDORSED]

The units used to calculate K and Q must be constant in the equation, so that the units will cancel out and leave K and Q without specific units, as K is a constant and Q is a ratio.