The Significance of K

[ALegala_2I]

When do you use Kc vs Kp?

[christabellej 1F]

You would use Kc when you are given molarity/concentrations of the reactants and products. If you are given partial pressure values, you can use Kp.

[Sydney Myers 4I]

Kc is the equilibrium constant calculated using the concentrations of the products and reactants, while Kp is the equilibrium constant calculated using the partial pressures of the products and reactants.

[Paul Hage 2G]

Also, Kp can only be used for gas phase reactions (because an aqueous reactant or product would not have a partial pressure value), whereas the Kc constant can be used for reactions where both gaseous and aqueous reactants/products would need to be considered while calculating the equilibrium constant.

[sarahforman_Dis2I]

Typically, molarity/concentration units are given when the products and reactants are in aqueous solution whereas partial pressure is given when the reactants and products are all in the gas phase. Ultimately, however, Kc and Kp give you the same information about a reaction.

[Michelle N - 2C]

In general, the significance of K is the same, since it states the equilibrium constant. Kc and Kp just basically denote what the units are. The C would stand for concentration (molarity) and the P would stand for partial pressure. Hope this helps!