Question

a 0.76 mol sample of pcl5 is placed in a 500 ml reaction vessel. what is the concentration of pcl5 when the reaction

pcl5(g) ⇀↽ pcl3(g) + cl2(g)

has reached equilibrium at 250◦c (when kc = 1.8)

Answer 1

kc= [x)(x)/(2*.76-x)= 1.8

x^2=1.8(1.52-x)
solve that quadratic for x

x^2+1.8x-2.74=0

x= (-1.8+-sqrt(3.24+10.96) )/2

x= -.9+- 3.77/2= ..985 moles/liter

or conce of Pcl5 is 2*.76-.985

check my math.