Chem 2
posted by Anonymous!! on .
Phosphorus pentachloride decomposes according to the chemical equation
PCl5<>PCl3 +Cl2
A 0.260 mol sample of PCl5(g) is injected into an empty 2.75 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
Please help I'm not sure where to go after you solved for x (Using the quadratic formula)
I got x=0.0921
is this correct? and how do i get the PCl5 and PCl3 from that?

I can't check this without knowing Kc.
If your value of x is correct that is the value of PCl3 and Cl2 because you probably did it this way.
........PCl5 ==> PCl3 + Cl2
I.......0.0945.....0.....0
C.........x.......x......x
E.......0.0945x...x......x
You can see x = (PCl3) = (Cl2) while (PCl5) = 0.0945x 
Sorry Kc is 1.8 at 250 degree C

You can check these things by substituting your value of x into the Kc expression and see if you come out with 1.8. I did this with 0.0921 and it doesn't pan out. When I solve the quadratic I obtained 0.09 for x and that checks out.