Question

2.5 g of protein containing only glycine (C2H5NO2) is dissolved in water to make 500 mL of solution. The osmotic pressure of this solution at 300 K is found to be 5.03 × 10–3 bar. The total number of glycine units present in the protein is _______.
(Given : R = 0.083 L bar K–1 mol–1)

Answer 1

The correct answer is 330
Since, π = icRT
$5.03×10^{−3}=\frac{2.5}{M}×\frac{1000}{500}×0.083×300$
Molar mass of protein = 24751.5 g/mol
Number of glycine units in protein
$=\frac{24751.5}{75}$ = 330
So, The total number of glycine units present in the protein is 330.