K vs. Kc

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Samantha Pedersen 2K
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K vs. Kc

Postby Samantha Pedersen 2K » Mon Jan 04, 2021 2:32 pm

Some of the textbook problems for Outline 1 ask us to refer to Table 5G.2 to find the equilibrium constant for a certain reaction and use it to solve the problem. For each reaction, there is a K value and a Kc value listed in Table 5G.2 and I've noticed that the two values are sometimes different. How do we know when to use K and when to use Kc? Thank you!
Last edited by Samantha Pedersen 2K on Mon Jan 04, 2021 2:44 pm, edited 1 time in total.

Anirudh Mahadev 1G
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Re: K vs. Kc

Postby Anirudh Mahadev 1G » Mon Jan 04, 2021 2:37 pm

In my understanding, K and Kc are almost interchangeable, but K is more general, while Kc is mainly used in the context of comparing concentrations. K can be used to cover both the equilibrium constant of concentrations, Kc, and the equilibrium constant of gas pressures, Kp. Dr. Lavelle with probably explain the difference more in detail in Wednesday's lecture when he explains how to calculate Kp. Hope this helps!

Madeline Ogden 3B
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Re: K vs. Kc

Postby Madeline Ogden 3B » Mon Jan 04, 2021 2:44 pm

I agree with the post above! K is a broad term for all equilibrium constants whereas Kc is a more specific term for equilibrium constants dealing with concentration.

Sabine Salvucci 2E
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Re: K vs. Kc

Postby Sabine Salvucci 2E » Mon Jan 04, 2021 2:47 pm

Hello! I think K and Kc are basically the same thing, both representing the equilibrium constant, but Kc is more specific. K can refer to concentration, pressure, etc., while Kc specifically refers to concentration. Hope this helps!

Sam_Marasigan_3D
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Re: K vs. Kc

Postby Sam_Marasigan_3D » Mon Jan 04, 2021 3:27 pm

I believe K is just the equilibrium constant. We differentiate it by using Kc or Kp.

Margaret Wang 2D
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Re: K vs. Kc

Postby Margaret Wang 2D » Mon Jan 04, 2021 3:28 pm

K is a broad term for the equilibrium constant. Kc and Kp are more specific versions of the equilibrium constant, although most of the time K means Kc (from my observations)

Alara Aygen 3K
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Re: K vs. Kc

Postby Alara Aygen 3K » Mon Jan 04, 2021 3:37 pm

They are used interchangeably.

My-Lan Le 1L
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Re: K vs. Kc

Postby My-Lan Le 1L » Mon Jan 04, 2021 3:48 pm

Like what all of the other posts say, they can be used interchangeably and basically are the same thing, but K is more general and Kc is referring to the concentrations. The c subscript is used to specify that the concentration is being used. I think in the next lectures, Dr. Lavelle will talk about other subscripts like p which refers to pressure.

Violet Kwan 3H
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Re: K vs. Kc

Postby Violet Kwan 3H » Mon Jan 04, 2021 3:54 pm

I also agree with the posts above. Since the difference between the two is small, they can basically be considered the same or used interchangeably. Just depends on which specific concentration you need or what the question calls for.

Jack_Pearce_2H
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Re: K vs. Kc

Postby Jack_Pearce_2H » Mon Jan 04, 2021 4:02 pm

Kc usually deals with equilibrium regarding concentrations and K is a more general term for the eq. constant. Hope this helps!

Adam Bustamante 1I
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Re: K vs. Kc

Postby Adam Bustamante 1I » Tue Jan 05, 2021 10:04 pm

K is an equilibrium constant, but Kc is understood as an equilibrium of concentration constant, so they're basically the same. K is just a broader term.

Crystal Pan 2G
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Re: K vs. Kc

Postby Crystal Pan 2G » Tue Jan 05, 2021 10:07 pm

K is the equilibrium constant and can be Kp or Kc. Kc is used for concentrations.

Nicolette Simoni 3L
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Re: K vs. Kc

Postby Nicolette Simoni 3L » Wed Jan 06, 2021 9:55 am

I agree with the statements above but one thing to also keep in mind is that when calculating the equilibrium constant from thermodynamic tables of data (the standard gibbs free energy for example), you have to give K, not Kc.

Megan Hulsy 1A
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Re: K vs. Kc

Postby Megan Hulsy 1A » Wed Jan 06, 2021 10:01 am

K is the generalized term for the equilibrium constant. Kc is just a specific format for concentrations! :)

Anna Yang 1A
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Re: K vs. Kc

Postby Anna Yang 1A » Wed Jan 06, 2021 11:38 am

K means equilibrium constant. Kc denotes its specification for concentrations while Kp denotes its specification for gases/pressure.

Annika Tamaki 1E
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Re: K vs. Kc

Postby Annika Tamaki 1E » Wed Jan 06, 2021 12:03 pm

K just represents concentration, whereas Kc represents the constant equilibrium concentration.


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