Question

At `25^(@)C`, a solution containing `0.2 g` of polyisobutylene in `100 mL` of benzene developed a rise of `2.4 mm` at osmotic equilibrium. Calculate the molecular weight of polyisobutylene if the density of solution is `0.88 g// mL`.

Answer 1

Height developed `= 2.4 mm`
Osmotic pressure `= h.d.g`
`= (2.4)/(10) xx 0.88 xx 981`
`= 207.187 "dyne" cm^(-2)`
Now `piV = nST`
`207.187 xx 100 = (0.2)/(m) xx 8.314 xx 10^(7) xx 298`
(`R` in erg, `V` in `mL`, using `CGS` system)
`m = 2.39 xx 10^(5)`