Question

10g of NOBr were added to a 5L flask and the temperature was fixed to 350K. The following equilibrium is reached : NOBr(g)=NO(g)+1/2Br2(g);The pressure measured at the equilibrium was 0.63 atm.Determine Kp and Kc.
I need help to solve this problem.I already done 50% but at the very end concentration of nitrocyl bromide is negative.I cant understand why its come.I need full solution of this problem.

Answer 1

Use PV = nRT and solve for p= pressure at the initial conditions listed. You can go through the math but I've estimated initial p = 0.05 atm. Of course you need a more accurate number than that.
......NOBr ==> NO + 1/2 Br2
I....0.05......0........0
C.....-p.......p.......p/2
E...0.05-p.....p.......p/2

At equilibrium,
0.05-p + p + 0.5p = 0.63 which allows you to calculate p at equilibrium. That's approx 0.3 atm. Determine equilibrium values for the components and solve for Kp. Then convert to Kc.
Post your work if you get stuck.