Question

Osmotic pressure of a solution containing 7 g of a protein per 100 mL of solution is 25 mm of Hg at${37}^{0}C$. Calculate the molecular mass of protein. R= 0.082 L atm $mo{l}^{-1}{K}^{-1}$.

• A. $10050g/mol$
• B. $92432g/mol$
• C. $25743g/mol$
• D. $54094g/mol$

Answer 1

The correct option is D $54094g/mol$

Osmotic pressure:

$\pi =\frac{n}{V}\times RT$
n is number of moles

$\pi =\frac{w\times RT}{M\times V}$

w is mass of solute
M is molecular mass of solute

Here ,
$\pi =25mmHg\Rightarrow \frac{25}{760}atmR=0.0821Latmmo{l}^{-1}{K}^{-1}w=7gT={37}^{\circ }C=310KV=0.1L$

$M=\frac{w\times RT}{\pi \times V}$

$M=\frac{7\times 0.082\times 310\times 760}{25\times 0.1}=54093.7g/mol$