Osmosis:
⇒ The movement of solvent molecules
through a semi-permeable membrane (kept between a pure solvent and its
solution) from pure solvent to solution is osmosis.
⇒ The movement of solvent molecules
continues till equilibrium is reached.
⇒ Solvent molecules move from lower
concentration solution to higher concentration solution.
Osmotic
pressure:
⇒ The excess pressure exerted on the
solution side to stop the movement of solvent molecules into the solution.
⇒ Depends on concentration of solution
At a given temperature,
π α C
π = CRT
π = Osmotic Pressure
C = molarity
R = gas constant
T = Temperature
Isotonic
solutions: Two solutions having same osmotic pressure
at a given temperature.
Hypertonic
solution: Any solution with a higher salt concentration than normal body cells so that the water is drawn out of the cells by osmosis. Hypertonic solutions have higher osmotic pressure.
Hypotonic solution:
Any solution with a lower concentration than normal body cells so that water flows into the cells by osmosis. Hypotonic solutions have lower osmotic pressure.
Reverse
Osmosis:
⇒ When pressure greater than osmotic
pressure is applied on the solution, the solvent molecules move from solution
to pure solvent. This is reverse osmosis
⇒ Used in sea water purification
⇒ Reverse osmotic pressure > osmotic
pressure.
Determination of molar
mass: We can determine the molecular weights of the
solute using colligative properties.
The molecular weight Relates with magnitude of
a colligative properties as.
Molecular Mass α 1/ Magnitude of colligative
property
1. From vapour
pressure:
Where, wA = mass of solvent
MA = Molar mass of solvent
WB = mass of solute
MB = Molar mass of solute
2. From boiling point:
M2 = molar mass of solute
W2= mass of solute
Kb = Molal elevation constant
∆Tb = elevation in boiling point
3. From freezing point:
M2 = molar mass of solute
W2= mass of solute
Kf = Molal depression constant
∆Tf = depression in freezing point
4. From osmotic
pressure:
M2 = molar mass of solute
R = gas constant
T = temperature
π = osmotic pressure
V = Volume of the solution in liters.
No comments:
Post a Comment