What is the molar mass of a protein, if a solution of 0.12 g of the protein in 0.040 L of solution has an osmotic pressure of 0.76 torr at 35

Question

What is the molar mass of a protein, if a solution of 0.12 g of the protein in 0.040 L of solution has an osmotic pressure of 0.76 torr at 35 C

Use R=0.08206L atmmol K in your calculation

Answer 1

∏ = iMRT.

∏ = osmotic pressure = 0.76 torr

i = van’t Hoff factor = 1 for a protein molecule

M = moles/liter = ?

R = gas constant = 62.36 L-torr/K-mol

T = temp in Kelvin = 35+273 = 308K

0.76 = (1)(M)(62.36)(308)

M = 0.00003957 mol/L

0.12 g/0.040 L = 3 g/ L

3 g = 0.00003957 moles

molar mass = 3 g/0.00003957 moles = 75,815 g/mol = 75.8 kD