Question

consider a device to register osmotic pressure, in which it is placed a solution containing 20 grams of hemoglobin in a liter of solution in the right compartment and pure water in the left compartment is placed. Explain the phenomenon that occurs and determine the molecular weight of the hemoglobin if at equilibrium, the water height of the right column is 77.8 mm above the left column if the temperature remains at 35 ° C

Answer 1

Answer: (A)

• Phenomenon of Osmotic Pressure: First let me tell you the meaning of osmosis. Osmosis can be said as filtration of liquid or passing of liquid molecules from thin layered material membrane or semi permeable membrane to the other side of the semi permeable wall.
• Now to know the osmotic pressure we generally consider two compartment adjacent to each other separated by semi permeable membrane. Now if we have Solvent in one compartment and solution other compartment, the solvent molecules (Pure liquid) will try to pass through the semi permeable membrane.
• Due to this process the level or height of liquid in solution compartment is significantly more than the compartment with pure solvent. Therefore the hydrostatic pressure is now more in solution compartment compared to solvent compartment. Hydrostatic pressure is just the pressure created by fluid at the bottom by considering its height, gravity and fluid density
• This difference in hydrostatic pressure is called Osmotic pressure.

Answer: (B) Problem: To determine molecular weight of hemoglobin (water solution) compartment

• Given values: 20 grams of hemoglobin in 1 lit water, helmoglobin (water solution) height = 77.8 mm more then pure water compartment, Temperature of fluid in both compartment is 35 Celsius or 308 K.

First we need to find,

the osmotic pressure, =

As no density of soluion is given in question I am assuming the density to be of water as the solution is highly diluted with water.

Putting all values in the osmotic pressure formula. We get

osmotic pressure, =

• To find the molecular weight of hemoglobin in 1 lit water solution:

We use, other formula of osmotic pressure,

where,

c, concentration of the hemoglobin in water solution = 20

R, Gas constant = 8.314

T, Temperature of fluid = 308 K

Z, Molecular weight of hemoglobin which is to find out

Now by putting all values of variable into the formula to find molecular weight of hemoglobin.

= 67.12 Kg/mol

molecular weight of hemoglobin in right compartment is 67.12 Kg/mol