An aqueous solution of BaCl2 (1.28gm in 100gm of water)boils at 100.0832∘ at 1 atm. Calculate the degree of dissociation. ( Kb of water is 0.512 k/m)
0.85
No. of moles of BaCl2=1.28208.34
=0.006 moles
∴molality=0.006×1000100=0.06 moles
△Tb=iKbm⇒△TbKbm=i⇒0.0830.512×0.06=i⇒i=2.7
Now consider the dissociation of BaCl2
BaCl2 → Ba + 2ClInitial: C 0 0final: C(1−α) cα 2Cα
i=C(1−α)+Cα+2CαC=1+2α⇒i=1+2α⇒2.7=1+2α⇒α=0.85