Question

an aqueous solution contains 12.25 g of a protein in a total volume of 425 ml.the solutions osmotic pressure is 1.34 torr at 22degree celcius .determine the proteins molar mass.

Answer 1

osmatic pressure = C * R * T

where, C = cocentration

osmatic pressure = 1.34 torr = 0.00176 atm

T = 22 + 273 = 295 K

0.00176 = C * 0.0821 * 295

0.00176 = C * 24.2

C = 0.00176 / 24.2 = 7.27*10^-5 M

cocentration = number of moles / volume of solution in L

7.27*10^-5 M = number of moles / 0.425 L

number of moles =  (7.27*10^-5) *0.425 = 3.09*10^-5 mole

number of moles = mass / molar mass

3.09*10^-5 mole = 12.25 g / molar mass

molar mass of protein = 12.25 g / 3.09*/10^-5 mole = 3.96*10^5 = 396000 g/mol

Therefore, the molar mass of protein = 396000 g/mol