Equilibrium Question?

Question

I need help with the following chemistry problem:

A 3.00 L vessel was charged with 0.123 atm of PCL5. What is the equilibrium partial pressure in atm of PCL3 if Kp = 0.0121?

PCl5 (g) -> PCl3 (g) = Cl2 (g)

Any answers would be very much appreciated! Thanks!

Answer 1

Easy! let's make sure I remember what I am doing

Kp= (Cl2)(PCl3)/(PCl5)=.0121

.0121=(Cl2)(PCl3)/.123

If Cl2=PCl3

.0015=(Cl2)(PCl3) or you could say (PCl3)^2 since they are equal......

Therefore, P(PCl3)=sqrt .0015=.0387 atm

Answer 2

You have to solve:

(x/3)squared/((0.123 - x)/3) = 0.121