Question

Find out the osmotic pressure of $0.1M$ monobasic acid, if $pH=2.0$ at $25^{\circ }C$.

• A. $2.69atm$
• B. $26.9atm$
• C. $0.269atm$
• D. None of these

Answer 1

Answer: (A)

$\left[H^{+}\right]=C\alpha$
$\left[H^{+}\right]=10^{-2}$
$[\because pH=2]$
$C\alpha =10^{-2}$
$\alpha =\frac{10^{-2}}{0.1}=0.1$
Total number of moles after dissociation
$=C-C\alpha +C\alpha +C\alpha =C(1+\alpha )$
van't Hoff factor $=\frac{C(1+\alpha )}{C}=1+\alpha$
$=1+0.1=1.1$
$\pi =iCRT=1.1\times 0.1\times 0.0821\times 298$
$=2.69atm$