Question

A 0.797 g sample of β‑galactosidase is dissolved in water to make 0.199 L of solution, and the osmotic pressure of the solution at 25 ∘C is found to be 0.853 mbar. Calculate the molecular mass of β‑galactosidase.

Answer 1

Molecular mass of β‑galactosidase = 1.16*10^5g

Step-by-step explanation:

The osmotic pressure (π) is related to the molarity (M) of a solution by the following equation:

`\Pi = i*M*R*T`

i = Von't hoff factor = 1 for non-electrolytes

R = gas constant = 0.0821Latm/mol-K

T = temperature

Based on the above equation, molarity of β‑galactosidase is:

`\M = (\Pi)/(iRT)=(0.000842atm)/(1*0.0821Latm/mol-K*(25+273)K))= 3.44*10^(-5)mol/L`

`Moles\ galactosidase=molarity*volume= 3.44*10^(-5)moles/L*0.199L=6.85*10^(-6) moles\\\\Molar\ Mass\ galactosidase = (mass)/(moles) =(0.797g)/(6.85*10^(-6)mol ) =1.16*10^(5) g`