0.500 g hemoglobin was dissolved in enough water to make 100.0 cm^3 of solution.

Question

0.500 g hemoglobin was dissolved in enough water to make 100.0 cm^3 of solution. At 25 degree C the osmotic pressure was found to be 1.78times10^3 atm. Calculate the molecular mass of the hemoglobin. the following osmotic pressures were measured for solutions of a sample of polyisobutylene in benzene at 25 oC, and the solution density is about 0.88 g/cm3 in each case: Calculate an average relative molecular mass The osmotic pressure of a PVC sample in acetone (density of the solution is 0.798 g/cm3) was measured at 298 K. Calculate the molar mass of the sample. The concentration dependence of the osmotic pressure of solutions of a macromolecule at 20 degree C was found to be as follows: Determine the molar mass of the macromolecule. Calculate the osmotic pressure exhibited by a 0.10M sucrose solution at 20 oC.

Explanation / Answer

Exercise 1:

Given = 0.500 g hemoglobin

Volume of solution = 100ml = 0.1L

T 250C = 25 +273 = 298K

Osmotic pressure = 1.78 × 10-3 atm.

Step1-

Calculate molarity of solution –

c = /RT

c =1.78 × 10^-3 atm/0.0821Latm/K.mol x 298K

c = 7.28 x 10^-5 M

Step2-

Calculate moles of hemoglobin in solution-

n = c V

n = 7.28 x 10^-5 M x 0.1L

n = 7.28 x 10^-6 moles

Step-3 Calculate molar mass of hemoglobin –

Molar mass = mass/moles

                     = 0.500g/ 7.28 x 10^-6 moles

                     = 68681.3187 g/mol

Molar mass of hemoglobin = 68681.33 g/mol

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