## K and Kc

Jose Torres
Posts: 31
Joined: Fri Sep 28, 2018 12:22 am

### K and Kc

Can someone explain to me the difference between K and Kc? When do you use one over the other? (I thought of this while looking at Topic 5H.3 or page 412 of the 7th edition book, just in case this helps)

Aurbal Popal
Posts: 63
Joined: Fri Sep 28, 2018 12:27 am

### Re: K and Kc

The way I understood it, Kc is for molar concentration. There's also Kp but that's for partial pressures for gases. I think K is just the equilibrium constant and Kc is just a more specific way of denoting what you are finding.

Samantha Chang 2K
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am

### Re: K and Kc

Kc is specifically the molar concentration [P]/[R], and K is just an overall equilibrium constant.

Sara Flynn 2C
Posts: 60
Joined: Fri Sep 28, 2018 12:23 am

### Re: K and Kc

I think that when just K is listed it usually is referring to Kp because the pressures give a more accurate value than the concentrations

Jordan Lo 2A
Posts: 85
Joined: Fri Sep 28, 2018 12:25 am

### Re: K and Kc

Do we need to memorize the formula in the book for converting between the 2?

Rian Montagh 2K
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: K and Kc

Jordan Lo 2A wrote:Do we need to memorize the formula in the book for converting between the 2?

My guess would be no, because we rarely if ever have to memorize any formulas.

Kavvya Gupta 1H
Posts: 35
Joined: Fri Sep 28, 2018 12:21 am

### Re: K and Kc

Jordan Lo 2A wrote:Do we need to memorize the formula in the book for converting between the 2?

The only formula you need anyway to convert between the two is the ideal gas law, PV=nRT which changes to P=concentrationRT. It's handy to know, but I don't think you need to memorize it.

Nicolle Fernandez 1E
Posts: 56
Joined: Fri Sep 28, 2018 12:25 am
Been upvoted: 1 time

### Re: K and Kc

K and Kc are the same thing but K can also represent Kp

Niveda_B_3I
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: K and Kc

You can determine whether you should be using Kc or Kp depending on the states of the molecules in the chemical equation, or also the information given to you.