Question

An aqueous solution containing 1.50g of an unknown protein per liter has an osmotic pressure of 0.00612 atm at 25c . Calculate the molar mass of this protein R=0.08206

Answer 1

The Osmotic pressure is given as:

P= MRT , where P is the osmotic pressure, M the molar concentration, R the gas constant (0.08206 L atm mol^-1 K^-1)

from the given equation one can calculate M by putting, P=0.00612 atm, T= 298 K , R=0.08206 L atm mol^-1 K^-1

M= 0.000250 mol L^-1

M is given as no. of moles per litre, and moles can be calculated as:

Given Mass/Molar Mass

Since the problem involves 1 litre, one can directly write

0.000250=1.50/Molar Mass

Molar Mass= 6000 g.