The degree of dissociation of Ca(NO3)2 in a dilute aqueous solution containing 7 g of salt in 100 g of water at 100∘C is 70%. The vapour pressure of solution is:
Therefore, total moles at equilibrium = 1+2α
=1+2×0.7 [As,α=0.7]=2.4
For Ca(NO3)2: mNmexp=1+2α
Therefore, mexp=mN(1+2α)=1642.4=68.33
Also at 100∘C,P0H2O=760 mm, w=7 g, W=100 g
And (P0−Ps)Ps=(7×18)(68.33×100)=0.0184P0Ps−1=0.0184∴ Ps=7601.0184=746.27 mm of Hg