Question

`x g` of non-electrolytic compound (molar mass =200) is dissolved in `1.0 L` of `0.05 M NaCl` solution. The osmotic pressure of this solution is found to be `4.92 atm` at `27^(@)C`. Calculate the value of `x`. Assume complete dissociation of `NaCl` and ideal behaviour of this solution.

Answer 1

(i) For NaCl : `pi_(1)=iCRT=2xx0.05xx0.0821xx300`
`=2.463` atm
(ii) For unknown compound :
`pi_(2)=CRT=(x)/(200)xx0.0821xx300=0.1231x` atm
Total osmotic pressure `pi=pi_(1)+pi_(2)`
`4.92 = 2.463+0.1231x`
`x = 19.959 g`.