## KC vs KP [ENDORSED]

Eden Breslauer-Friedman 2A
Posts: 104
Joined: Wed Sep 30, 2020 10:11 pm

### KC vs KP

If we are given a chemical reaction that has gases involved, do we automatically assume we are calculating KP, or does it depend if we are given values in molar concentrations, or atmospheres/bars?

Thanks!

Andrew Wang 1C
Posts: 90
Joined: Wed Sep 30, 2020 10:11 pm
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### Re: KC vs KP

It would depend if we are given the values of reactants/products in concentration or bars. I remember some problems in the Audio-Visual modules had us calculate Kc when there were only gases in the reaction.

SahajDole_1C
Posts: 96
Joined: Wed Sep 30, 2020 9:33 pm

### Re: KC vs KP

Usually the question should mention what to find but it would depend on the values given.

Jonathan Batac - 2D
Posts: 99
Joined: Wed Sep 30, 2020 10:03 pm

### Re: KC vs KP

I would always check what units are given. As you stated, if given concentration (Molarity) usually you would be calculating for Kc, and if given atm/bars usually you would be calculating for Kp.

Gabriel Nitro 1E
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### Re: KC vs KP

Hi,

It entirely depends on the context on what you are given. If you are given any information which may lead you to find concentrations ($mol, M, mmol, L, mL, g, mg$), use $K_c$. If you are given any information which may lead you to find partial pressures ($PV = nRT, atm, bars, mm Hg$), then use $K_p$.

Hope this helps! :)

Kareena Patel 1G
Posts: 92
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### Re: KC vs KP

If the equation only involves gases, I think it is safe to assume that you should use Kp for the problem.

Kelly Tran 1J
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### Re: KC vs KP  [ENDORSED]

The units will tell you whether you are calculating for Kc or Kp. If the molar concentration is given, you are calculating for Kc. If the units of atm/bar is given, you are calculating for Kp.