Kp Units

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Vy Lu 2B
Posts: 59
Joined: Fri Sep 28, 2018 12:24 am

Kp Units

Postby Vy Lu 2B » Sun Jan 13, 2019 3:55 pm

Which units do we use when evaluating the equilibrium constant with partial pressure? Is atmosphere used or bar used?

Nicklas_Wright_1A
Posts: 60
Joined: Fri Sep 28, 2018 12:23 am

Re: Kp Units

Postby Nicklas_Wright_1A » Sun Jan 13, 2019 4:11 pm

It does not matter.

Alyssa Bryan 3F
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Re: Kp Units

Postby Alyssa Bryan 3F » Sun Jan 13, 2019 5:18 pm

Equilibrium constants (Kp) will not have units for your final answer, so while you are evaluating with partial pressure the units do not matter as long as all the partial pressures have the same units.

Ryan Troutman 4L
Posts: 68
Joined: Fri Sep 28, 2018 12:22 am

Re: Kp Units

Postby Ryan Troutman 4L » Sun Jan 13, 2019 5:29 pm

K values will not have units because they are "active" or "activities." Page 400 in the 7th Edition explains how activities are pure numbers and are unit less. More importantly, if you solve for K, you have (mol/L) / (mol/L), which cancel out leaving no units. So Kc and Kp will always be unit less, but you must ensure that when calculating for Kc and Kp the units are correct!

204929947
Posts: 76
Joined: Fri Apr 06, 2018 11:03 am

Re: Kp Units

Postby 204929947 » Sun Jan 13, 2019 7:20 pm

As mentioned by Lavelle, units do not matter because they will cancel out.

Dong Hyun Lee 4E
Posts: 68
Joined: Fri Sep 28, 2018 12:23 am

Re: Kp Units

Postby Dong Hyun Lee 4E » Sun Jan 13, 2019 7:33 pm

Kp will not use units as when calculating Kp with units you can see that the top and bottom units cancel out leaving only a number as the final answer.

Mikka Hoffman 1C
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Re: Kp Units

Postby Mikka Hoffman 1C » Sun Jan 13, 2019 7:37 pm

Kp doesn't have units because they cancel out, so I don't think it matters as long as you use the same units throughout your calculations


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