[alimarie]

I need help on this problem. I have no idea how to solve it! Please reply A.S.A.P. it's due in a few hours.  

Consider the reaction:
2SO2(g) + O2(g) --> 2SO3(g) at constant temperature. Initially a container is filled with pure SO3(g) at a pressure of 2 atm, after which equilibrium is allowed to be reached. If y is the partial pressure of O2 at equilibrium, the value of Kp is:

 A.
(2 - 2y)2
-------
(y2)(2y)

 B.
(2 - y)2
-------
(y2)(y/2)

 C.
(2 - y)2
-------
(2y)2(y)

 D.
(2 -2y)2
-------
(2y)2(y)

 E. none of these

[Borek]

First, write down expression for Kp.

Second, write down equilibrium amounts of all substances. You know what was initial pressure of SO₃, all pressures can be calculated using something like ICE table.

Finally, substitute.

[alimarie]

I don't know what to se for Kp, can you guide me exactly what to do pleasE?