## Converting K back to Kc

$\ln K = -\frac{\Delta H^{\circ}}{RT} + \frac{\Delta S^{\circ}}{R}$

kennedyp
Posts: 56
Joined: Tue Nov 13, 2018 12:18 am

### Converting K back to Kc

What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure.

kennedyp
Posts: 56
Joined: Tue Nov 13, 2018 12:18 am

### Re: Converting K back to Kc

Also, do you guys think points would be deducted on the test if we don't convert back to Kc after finding the new K?

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

### Re: Converting K back to Kc

I think Kc can signify K for all intents and purposes at least on the test. Kc is generally most used for the equilibrium constant for a rxn that is made up of aqueous solutions though, and Kp for for gases since Kc stands for concentration and Kp stands for pressure.

805097738
Posts: 180
Joined: Wed Sep 18, 2019 12:20 am

### Re: Converting K back to Kc

kennedyp wrote:What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure.

aren't those the same

kennedyp
Posts: 56
Joined: Tue Nov 13, 2018 12:18 am

### Re: Converting K back to Kc

805097738 wrote:
kennedyp wrote:What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure.

aren't those the same

Not according to the book :( Look at the very last part of section 5J.3, it talks about converting K to Kc when using Van't Hoff equation for gases

905373636
Posts: 62
Joined: Thu Aug 01, 2019 12:15 am

### Re: Converting K back to Kc

kennedyp wrote:
805097738 wrote:
kennedyp wrote:What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure.

aren't those the same

Not according to the book :( Look at the very last part of section 5J.3, it talks about converting K to Kc when using Van't Hoff equation for gases

So, isn't it just a unit conversion of atm or whatever has units to mol/L?