converting Kc to Kp


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Parker Smith
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Joined: Thu Jul 25, 2019 12:15 am

converting Kc to Kp

Postby Parker Smith » Thu Jan 09, 2020 5:46 pm

when using the ideal gas equation to convert Kp to Kc, do we need to know the volume, or do we just keep our value in molar and omit knowing the volume?

Alice Ma 2K
Posts: 52
Joined: Wed Nov 13, 2019 12:26 am

Re: converting Kc to Kp

Postby Alice Ma 2K » Thu Jan 09, 2020 5:50 pm

If you know the molar concentration, you technically do know volume because molar concentration is mol per liter. For example, if there is 0.3 mol/L of a reactant, that means the volume is one liter. Hope that answered your question!

Sartaj Bal 1J
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Joined: Thu Jul 25, 2019 12:17 am

Re: converting Kc to Kp

Postby Sartaj Bal 1J » Thu Jan 09, 2020 6:22 pm

For our purpose, we are mainly using the ideal gas equation to convert between concentration and partial pressure for a gas so I don't believe it's necessary to know the volume.

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

Re: converting Kc to Kp

Postby 805097738 » Thu Jan 09, 2020 6:55 pm

the volume is already included in the concentration as it is moles over volume

Megan Kirschner
Posts: 46
Joined: Wed Feb 20, 2019 12:17 am

Re: converting Kc to Kp

Postby Megan Kirschner » Thu Jan 09, 2020 7:58 pm

What exactly is the difference between Kc and Kp? I know (or think) they are equilibria constants but what do they individually represent?

Lizette Noriega 1H
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Joined: Wed Sep 18, 2019 12:15 am

Re: converting Kc to Kp

Postby Lizette Noriega 1H » Thu Jan 09, 2020 8:54 pm

Megan Kirschner wrote:What exactly is the difference between Kc and Kp? I know (or think) they are equilibria constants but what do they individually represent?


Kc is used for the concentration of aqueous solutions and gases while Kp is for the partial pressures of gases

Naren_Ramesh_4F
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Joined: Sat Aug 17, 2019 12:18 am

Re: converting Kc to Kp

Postby Naren_Ramesh_4F » Fri Jan 10, 2020 3:03 pm

When asked the equilibrium constant of a chemical reaction involving gases, do we solve for Kc or Kp?

Pegah Nasseri 1K
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Joined: Wed Feb 27, 2019 12:15 am

Re: converting Kc to Kp

Postby Pegah Nasseri 1K » Fri Jan 10, 2020 3:55 pm

Kc is calculated using molar concentration while Kp is calculated using partial pressures. To convert from Kc to Kp, use the equation PV=nRT. We know that the molar concentration is calculated by n/V so this equation can be manipulated to find the concentration which is concentration = n/V= P/RT. For gases, use partial pressures to calculate the K constant, unless the question specifically asks you to find Kc. For aqueous solutions, use molar concentrations to find the K constant.

Kassidy Ford 1I
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Re: converting Kc to Kp

Postby Kassidy Ford 1I » Sat Jan 11, 2020 3:25 pm

Naren_Ramesh_4F wrote:When asked the equilibrium constant of a chemical reaction involving gases, do we solve for Kc or Kp?

The question will probably ask what to solve for; either Kc or Kp, because for gases you can solve for either. if they give you partial pressures in the question than solve for Kp and if they give you concentrations than solve for Kc. K is unitless so it shouldn't matter

Jasmine Kim 1L
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Joined: Fri Aug 02, 2019 12:16 am

Re: converting Kc to Kp

Postby Jasmine Kim 1L » Sat Jan 11, 2020 4:10 pm

Naren_Ramesh_4F wrote:When asked the equilibrium constant of a chemical reaction involving gases, do we solve for Kc or Kp?

If the reaction involves gases, we will most likely be solving for Kp unless the question specifically asks us for Kc, in which case we will need to convert from Kp to Kc.

Jesse H 2L
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Re: converting Kc to Kp

Postby Jesse H 2L » Sun Jan 12, 2020 12:56 pm

is it better to convert all values of Kc to Kp before continuing to solve a problem (making an ICE table and so on...) using the ideal gas equation, or is it better to do it as the textbook instructs?

Viviana Velasquez
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Joined: Sat Jul 20, 2019 12:15 am

Re: converting Kc to Kp

Postby Viviana Velasquez » Sun Jan 12, 2020 9:00 pm

Naren_Ramesh_4F wrote:When asked the equilibrium constant of a chemical reaction involving gases, do we solve for Kc or Kp?

You would solve for Kp since the P stands for partial pressure. Remember that if they ask for the equilibrium constant of a gas always assume you use Kp unless stated otherwise.

Naren_Ramesh_4F
Posts: 105
Joined: Sat Aug 17, 2019 12:18 am

Re: converting Kc to Kp

Postby Naren_Ramesh_4F » Mon Jan 13, 2020 1:41 pm

Cool! Thank you so much!

AniP_2D
Posts: 95
Joined: Sat Aug 17, 2019 12:17 am

Re: converting Kc to Kp

Postby AniP_2D » Mon Jan 13, 2020 3:19 pm

If you know the molar concentration, then you should technically be able to figure out the volume.


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