Question

Calculate the osmotic pressure of a solution containing 16.75 mg of hemoglobin in 13.6 mL of solution at 32 ∘C . The molar mass of hemoglobin is 6.5×104 g/mol.

Answer 1

Mass of hemoglobin = 16.75 mg = 0.01675 g

Moles of hemoglobin = mass of hemoglobin / Molar mass of hemoglobin = ( 0.01675/6.5x10^-4)

    = 2.577 x 10^-7

volume of solution = 13.6 ml = 0.0136 L

Molarity = moles of hemoglobin / solution vol in L = ( 2.577x10^-7) / ( 0.0136) = 1.8948 x 10^ -5 M

Now we use formula for osmotic Pressure   P = C RT where T = 32C = 32+273 = 305 K

            = ( 1.8948 x 10^-5) x ( 0.08206 ) x ( 305)

          = 4.74 x 10^ - 4 atm