Different types of K

Chloe Alviz 1E
Posts: 102
Joined: Sat Aug 17, 2019 12:17 am

Different types of K

What's the difference between K and Kc?

Jessica Katzman 4F
Posts: 35
Joined: Mon Jun 17, 2019 7:24 am

Re: Different types of K

K is the general notation for the equilibrium constant. Kc is used when we are specifically defining the ratio of the molar concentrations of products and reactants.

Hussain Chharawalla 1G
Posts: 100
Joined: Sat Jul 20, 2019 12:15 am

Re: Different types of K

K is the equilibrium constant. It gives you the ratio between products and reactants. It can represent Kc or Kp

Kc is the equilibrium constant written in terms of concentration. So it is concentration of products over reactants.

Kp is the equilibrium constant in terms of partial pressure.

Emil Velasco 1H
Posts: 96
Joined: Wed Nov 21, 2018 12:19 am

Re: Different types of K

K = Kc = Kp

They are just different notations for whatever phase your equation is dealing with (e.g. gas w/ pressure)

Similarly, K = Q = Qc = Qp

Anna Chen 1K
Posts: 104
Joined: Thu Jul 25, 2019 12:18 am

Re: Different types of K

K is the equilibrium constant.
Kc is defined by molar concentrations while Kp is defined by the partial pressures of the gasses.

chari_maya 3B
Posts: 108
Joined: Sat Sep 07, 2019 12:18 am

Re: Different types of K

How do you convert from Kc to Kp?

Sydney Pell 2E
Posts: 100
Joined: Wed Sep 11, 2019 12:17 am

Re: Different types of K

The notation of K depends on what information they give you in the equation and what phase it occurs in. If the problem gives you the partial pressures of the gases in the reaction, you would be using Kp. If the molar concentrations are given, then Kc. Either way, K always stands for the equilibrium constant.

Vuong_2F
Posts: 90
Joined: Sat Sep 14, 2019 12:17 am

Re: Different types of K

chari_maya 3B wrote:How do you convert from Kc to Kp?

Lavelle hasn't mentioned anything about this in lecture so I'm not sure if this is necessary information, but the relationship between the two is Kp=Kc(RT)^Δn

AGaeta_2C
Posts: 112
Joined: Wed Sep 18, 2019 12:21 am

Re: Different types of K

chari_maya 3B wrote:How do you convert from Kc to Kp?

I believe this was briefly discussed in the second lecture. To convert between partial pressure and concentration for a gas, you use the Ideal Gas Equation, PV=nRT.
Where, P= pressure, V= volume, n= number of moles, and (RT) are constants.
To calculate pressure of a gas when you know its concentration, rearrange the equation:

P = (n/V)(RT)
P = (conc)(RT)

To calculate concentration of a gas when you are given its pressure, rearrange the equation:

(n/V) = (P/(RT))
(conc) = (P/(RT))

Jack Riley 4f
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

Re: Different types of K

K is the general equilibrium constant while Kc specifically refers to the equilibrium constant of molar concentrations