Question

Initially 0.8 mole of pcl5 and 0.2 mole of pcl3 are mixed in 1litre vessel.At equilibrium 0.4 mole of pcl3 is present.The value of kc

Answer 1

Hello dear,

● Answer - 0.133

◆ Explanation-
The reaction is given by,
Reaction PCl5 ---> PCl3 + Cl2
Initially 0.8 0.2 0
Equilibrium 0.8-x 0.2+x x

We have, at equilibrium
[PCl3] = 0.2+x = 0.4
x = 0.2

Hence,
[PCl5] = 0.8-x = 0.6
[PCl3] = x = 0.2+x = 0.4
[Cl2] = x = 0.2

For this reaction, equilibrium constant is given by,
Kc = [PCl3][Cl2] / [PCl5]
Kc = 0.4×0.2 / 0.6
Kc = 2/15
Kc = 0.133

Hope this is useful...