Textbook Table 5G.2

[Cecilia Cisneros 1F]

When we refer to the textbook table for the homework problems how do we know which equilibrium constant to use? I used a Kc value for a question asking to find the equilibrium concentrations, but the homework used the K value. I assumed that K by itself should only be used for finding partial pressures? (For reference the two values were different for this reaction so I went with Kc rather than K).

[OwenSumter_2F]

K is the more common equilibrium constant, and as a general rule we will most likely be working with K, as that is what a reaction will tend to level off to.

[Darlene Lien 3E]

Hi, so when the homework tells you to look at Table 5G.2 for the K value, you look at the temperature they give you in the problem and then locate the K value that has that respective temperature. Hope this helps!

[Lisa Seidl 3H]

When you are calculating for the equilibrium constant from the thermodynamics table (using Gibbs free energy for example) then you can only use K but other than that you can use Kc if you want to find the equilibrium in terms of molar concentration rather than partial pressure.

[Sreeram Kurada 3H]

Yeah, I think K is just a general term referring to the equilibrium constant, and Kp and Kc are specific into whether they are calculating for the equilibrium constant based on pressure or concentration.