Question

\(200 \mathrm{~cm}^{3}\) of an aqueous of a protein contains \(1.26 \mathrm{~g}\) of the protein. The osmotic pressure of such a solution at \(300 \mathrm{~K}\) is found to be \(2.57 \times 10^{-3}\) bar. Calculate the molar mass of the protein.

Answer 1

\(\pi=\frac{W_{B} R T}{M_{B} V}\)
\(M_{B}=\frac{W_{B} R T}{\pi V}\)
\(=\frac{1.26 \mathrm{~g} \times 0.083 \mathrm{Lbar} K^{-1} \mathrm{~mol}^{-1} \times 300 \mathrm{~K}}{2.57 \times 10^{-3} \mathrm{bar} \times 0.2 L}\)
\(=61,039 \mathrm{~g} \mathrm{~mol}^{-1}\)