Question

The plots of osmotic $\pi ($ in $atm$ ) vs. concentration (in $g/$ $c{m}^3$ ) of a polymer at $300K$ gives a straight line having slope $2\times 10^{-3}$. The molar mass of polymer is :

• A. $1.23\times 10^6$
• B. $1.23\times 10^7$
• C. $4\times 10^7$
• D. $4\times 10^6$

Answer 1

Answer: (B)

$\pi =\frac{CRT}{V}=\frac{wRT}{m\cdot V_{in}L}$

$=\frac{w\times RT\times 1000}{m\times V_{in}mL}$

$\pi =\frac{1000RT}{m}\times C_{g/c{m}^3}$

$\therefore$ slope $=\frac{1000RT}{m}=2\times 10^{-3}$

$\therefore m=\frac{1000\times 0.0821\times 300}{2\times 10^{-3}}$

$=1.23\times 10^{7}gmo{l}^{-1}$