Question

Derive the values of K and K for dissociation of PCI₅.

Answer 1

Consider that ‘a’ moles of PCl₅ is taken in container of volume ‘V’ Let x moles of PCI₅ be dissociated into x moles of PCI₃ and x moles of Cl₂.

	PCl5	PCl3	Cl2
Initial number of moles	a	0	0
Number of moles reacted	x	0	0
Number of moles at equlibrium	a - x	x	x
Active mass	(a - x) / V	x / V	x / V

Applying law of mass action

Where ‘n’ is the total number of moles at equilibrium

n = a - x + x + x = a + x