Question

The equivalent conductivity of acetic acid at infinite dilution is $390.6Sc{m}^{2}eq{v}^{-1}$ and for a certain concentration C of acetic acid solution it is $78.12Sc{m}^{2}eq{v}^{-1}$. The osmotic pressure of the same solution with concentration C of acetic acid is found to be 14.76 atm at 300 K. What is the value of C? (Take R= 0.082 atm-L/molK)

Answer 1

The degree of dissociation, $\alpha =\frac{{\Delta }^C}{{\Delta }^{\infty }}=\frac{78.12}{390.6}=0.2$

So, the value of van't Hoff factor, $i=1+0.2=1.2$
Osmotic pressure $\pi =i\times M\times S\times T\Rightarrow 14.76=1.2\times M\times 0.082\times 300$
$\Rightarrow M=0.5M$