Calculations

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Jennifer Torres 2L
Posts: 62
Joined: Tue Nov 14, 2017 3:01 am

Calculations

Postby Jennifer Torres 2L » Tue Jan 08, 2019 10:04 pm

Can someone explain the difference in calculating K, Kc And Kp.

Vincent Li 4L
Posts: 48
Joined: Fri Sep 28, 2018 12:19 am

Re: Calculations

Postby Vincent Li 4L » Tue Jan 08, 2019 10:11 pm

There isn't any mathematical difference in calculating K, Kc, or Kp. The subscripts c and p simply indicate how you're measuring the presence of your reactants and products. Kc is the equilibrium constant calculated from molar concentrations (of the units mol * L^-1), whereas Kp is the equilibrium constant calculated from pressure (bar or atm, which are about the same).

If given an example equation aA + bB ⇄ cC + dD, K, Kc, and Kp will all be calculated as (C^c * D^d) / (A^a * B^b). The only difference is if we are asked to calculate it using partial pressures or molar concentrations.

Melissa Villanueva1K
Posts: 64
Joined: Wed Nov 15, 2017 3:01 am

Re: Calculations

Postby Melissa Villanueva1K » Sun Jan 13, 2019 10:38 pm

Essentially K and Kc are in a sense asking for the same thing, which has to do with concentrations. Kc is in terms of molar concentrations. While Kp is the partial pressures of the gases included in the system. Q can be thrown into this category as well. When the problem is asking for K and you see that the compounds or molecules are all in gaseous states, then you are essentially looking for partial pressure, Kp.


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