## Using Kc Vs Kp

Rodrigo2J
Posts: 102
Joined: Sat Jul 20, 2019 12:16 am

### Using Kc Vs Kp

When a question asks us to identify the equilibrium expression for K, can we use either Kp (use partial pressures for the expression) or Kc (use concentrations for the expression)? or do we have to use a specific one in certain situations?

Astrid Lunde 1I
Posts: 103
Joined: Sat Sep 07, 2019 12:16 am

### Re: Using Kc Vs Kp

The units in the question should help you find out when to use Kc and Kp. Kc is in M and Kp is in Bar.

Kallista McCarty 1C
Posts: 212
Joined: Wed Sep 18, 2019 12:18 am

### Re: Using Kc Vs Kp

You should be able to tell based on the question that is being asked!

805307623
Posts: 99
Joined: Fri Aug 09, 2019 12:17 am

### Re: Using Kc Vs Kp

It might be helpful to pay close attention to the chemical equation and see if the molecules being used are identified as (l),(g),(aq).

Edmund Zhi 2B
Posts: 118
Joined: Sat Jul 20, 2019 12:16 am

### Re: Using Kc Vs Kp

I believe you should look at the states of matter and try and determine from that

Megan Cao 1I
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Joined: Sat Sep 07, 2019 12:18 am

### Re: Using Kc Vs Kp

Kc is generally used when you're given molar concentrations of solutions and Kp is generally used when you're given partial pressures.

faithkim1L
Posts: 105
Joined: Fri Aug 09, 2019 12:17 am

### Re: Using Kc Vs Kp

Kp is used for gases. Kc can be used for aqueous solutions. It's best to just go by the equation. Remember Kp is in pressure units and Kc is for concentration (M).

Shail Avasthi 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

### Re: Using Kc Vs Kp

If you're looking at aqueous equilibrium, use Kc. If looking at gasses, you can either use Kc or Kp. Use the question to determine the proper answer.

Eva Zhao 4I
Posts: 101
Joined: Sun Sep 29, 2019 12:16 am

### Re: Using Kc Vs Kp

Kp can only be used when reactants and products are gases. Kc can be used for gases or aqueous substances, but you should check the units involved to ensure you're using the right K.

205291012
Posts: 50
Joined: Mon Nov 11, 2019 12:17 am

### Re: Using Kc Vs Kp

This depends on the information given in the question. I believe even if the molar concentrations of gases is given then you would just calculate Kc. But if the partial pressures are given then calculate Kp.

Mariah
Posts: 104
Joined: Fri Aug 02, 2019 12:16 am

### Re: Using Kc Vs Kp

It just depends on what is given at the beginning and what is being asked for.

bellaha4F
Posts: 104
Joined: Wed Sep 18, 2019 12:20 am

### Re: Using Kc Vs Kp

if all the components are gases, use kp. if all aqueous, use kc. (unless the test question says otherwise)

Kristina Rizo 2K
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

### Re: Using Kc Vs Kp

I know the units for Kc is molarity, but could someone give the units to know if it is partial pressure.

Leonardo Le Merle 1D
Posts: 56
Joined: Wed Feb 27, 2019 12:16 am

### Re: Using Kc Vs Kp

There is no unit for Kc or Kp, it is simply a value used to represent the ratio of product and reactant concentration at equilibrium

705367472
Posts: 22
Joined: Tue Nov 19, 2019 12:19 am

### Re: Using Kc Vs Kp

When trying to find Kc or Kp you would use the same equation of product over reactants just like finding Q?

605395381
Posts: 50
Joined: Mon Jun 17, 2019 7:24 am

### Re: Using Kc Vs Kp

It would depends on the chemical equation given

vanessas0123
Posts: 100
Joined: Wed Sep 11, 2019 12:17 am

### Re: Using Kc Vs Kp

You use Kc when given concentrations, and Kp when given partial pressures.

Trent Yamamoto 2J
Posts: 111
Joined: Sat Aug 17, 2019 12:18 am

### Re: Using Kc Vs Kp

You would use Kc when given molar concentrations of solutions in any state and Kp when you're given partial pressures only in the gas state

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

### Re: Using Kc Vs Kp

If you are given concentrations, then you should use Kc. If you are given gases, then you should use Kp.