A gaseous reaction mixture contains SO2, Cl2, and SO2Cl2 in a 2 L container with the gases having the following partial pressures: P(SO2)=0.35 atm, P(SO2Cl2)=0.19 atm, P(Cl2)=0.24 atm. Kp=91 for the equilibrium system:

Question

SO2 (g) + Cl2 (g) -> SO2Cl2 (g)
Is the system at equilibrium?

I thought that to solve this I had to do something with Qc, but we have Kp and not Kc and you can't compare Kp and Qc, so I am really really confused. PLEASE HELP!

You can do it the long way, then check the short way and see if they are the same.
Using partial pressure and V = 2L, calculate mols and calculate mols/2L for concentration.
Then change Kp to Kc and use Qc.
That way you will be sure what you are doing is legitimate.

Then try just using Qp the same way you would use Qc but substitute partical pressures to arrive at Qp. See if the equilibrium is attained by going the same direction.