Posted by Robby on Sunday, February 10, 2013 at 12:25pm.
2NF3(g) yields N2(g) + 3F2(g)
When 2.06 mol of NF3 is placed in a 2.00L container and allowed to come to equilibrium at 800K, the mixture is found to contain 0.0227 mol of N2. What is the value of Kp at this temp?
1.91 X 103
1.73 X 106 (think this is it)
4.43 X 107
1.83 X 103

Chemistry  DrBob222, Sunday, February 10, 2013 at 3:22pm
I didn't get that. Post your work and I'll look for the error.

Chemistry  Robby, Sunday, February 10, 2013 at 4:01pm
I think I tried to do the ICE and got...
2.06/2.00=1.03 M
0.0227/2.00=0.0114 M
but got lost after that and ended up with 1.73 X 106...I am really struggling on these problems... 
Chemistry  DrBob222, Sunday, February 10, 2013 at 4:18pm
I think you started out wrong. The problem gives as Kp and you are calculating, by mols/L, the concn. You put pressures in Kp and concns in Kc.
........2NF3 ==> N2+ 3F2
I......2.06mols...0....0
C.,.....2x.... .x....3x
E.....2.06x......x....3x
The problem tells you that x(N2) is 0.0227 mols. That makes F2 = 3*0.0227 and mols NF3 = 2.06 (2*0.0227)
Now convert 0.0227 to pressure using PV = nRT and do the same to find pressure of F2 and NF3. The substitute into Kp expression and solve for Kp.
My answer was 0.00190