Question

Osmotic pressure of $0.2M$ aqueous solution of $MgC{l}_2$ at $300K$ is $4.92atm$. what will be the percentage ionization of the salt?

• A. $79$
• B. $59$
• C. $34.5$
• D. $69$

Answer 1

The correct option is C $34.5$

The external pressure which must be applied on solution side to stop the process of osmosis is called osmotic pressure of the solution. It is calculated as $\pi =\Sigma i_n{C}_{n}RT$

In this case $\pi NaCl=0.1\times 2RT$

$\pi N{a}_{2}S{O}_4=0.2\pi 3RT$

and $\pi HA=0.5RT\times 1.2R$

the ideal gas constant $=0.082lit.atm.mo{l}^{-1}{K}^{-1}$

$=\pi =0.0821\times 300(0.2+0.6+0.6)=34.482atm$