A 0.004 M solution of Na2SO4 is isotonic with a 0.010 M solution of glucose at same temperature. The apparent precentage degree of dissociation of Na2SO4 is:
Isotonic solution:
Two solutions having the same osmotic pressure across a semipermeable membrane is referred to as an isotonic solution
Osmotic pressure,
π(Na2SO4)= iCRT=(0.004)iRT
π(glucose)=CRT=0.010RT ∵i=1 for non-electrolyte
As solutions are isotonic,
i(0.004)RT=0.01RT
i=2.5
Na2SO4 ⇌2Na++SO2−4
1 mol 0 0
1−α 2α α,
n=3
we know,
i=1+α(n−1)
i=1+2α
α=i−12=2.5−12=1.52=0.75=75%