Aqueous and Gaseous Phases

[Deap Bhandal L1 S1J]

If a chemical reaction has both aqueous and gaseous substances, how would you determine K if given the concentrations? Would you use Kp or Kc? Also if using Kc, are gases included? Dr. Lavelle said only solid and liquids were excluded in the calculation.

[Lucian1F]

If there are both gases and aqueous molecules in a reaction then you will need to use PV=nRT to find the concentration of the gases, then find Kc.

[Mishta Stanislaus 1H]

Could someone please expand on this answer?

[Janet Nguyen 2H]

It depends what is given in the problem. If the concentrations of all the reactants, whether gaseous or aqueous, are given, then it is safe to use Kc. If the pressure is given for the gaseous phases, then you would need to use pv=nrt to find the concentrations by first finding n (the number of moles) and then dividing it by the volume of the container, and use Kc. However, we shouldn't be encountering any problems that deal with that equation because I don't think we are touching on it in this class or at least the test.