Question

Kc for pcl5 is 0.04 at 250c how many moles of pcl5 must be added

Answer 1

Hii dear,

# Answer- 0.25 moles

# Explaination-

Consider a as initial concentration of PCl5 and x be degree of dissociation.

Dissociation of PCl5 takes place according to following reaction

PCl5 → PCl3+Cl2

Initial conc: a 0 0

Final conc : a(1-x) ax ax

[Cl2] = 0.1 = ax ...(1)

Kc = ([PCl3][Cl2])/ [PCl5]

0.04 = (ax. ax)/a(1-x)

Solving this we'll get,

x=0.4

From (i)

a = 0.1/0.4 = 0.25

Hence, we can say moles of PCl5 added is 0.25 moles.

Hope that cleared your doubt.