Solutions | Osmotic Pressure | 12th Chemistry | By. Mrs. Shubhada Walawalkar

It discusses about semipermeable membrane, osmosis, osmotic pressure,relation between osmotic pressure and concentration and molar mass of solute, Isotonic ,hypertonic,hypotonic solutions,Reverse osmosis.

1. Chemistry
12
th
science
2.Solutions
Colligative properties of Nonelectrolyte
solutions.
Osmotic pressure(π)

2. ➢Semipermeable membrane(Natural and artificial membrane)
➢Osmosis
➢Osmotic pressure
➢Isotonic, Hypertonic, Hypotonic solutions
➢Osmotic pressure and concentration relation
➢Osmotic pressure and molar mass of solute
➢Reverse Osmosis

3. ➢Wilted flowers revive
when placed in fresh
water
➢Dry fruits placed in
water get swollen

4. Semipermeable membrane:-
Semipermeable membrane is a
film such as cellophane which
allow the solvent molecules to
pass through them.
1)Natural membrane
2)Artificial membrane

5. Natural membrane –vegetable origin
Dry grapes onion membrane Egg membrane

6. –Cu
2[Fe(CN)
6]
Copper ferrocyanide
Artificial membranes:-
Cellophane paper Parchment paper Inorganic ppt

7. Osmosis:
The spontaneousflow of solvent
molecules through
semipermeablemembrane from
its highconcentration to its low
concentration. (The vapour
pressure of solvent is greater than
that of solution)

8. The amount of liquid on the pure
solvent side or more dilute
solution side decreases. While
the amount of liquid on other
side increases.
This results in decrease of the
concentration of solution.

9. Osmotic Pressure(??????):-
The hydrostatic pressure that stops osmosis is an
osmotic pressure. OR
The hydrostatic pressure built up on the solution
which just stops the osmosis.
Osmotic pressure = hydrostatic pressure
??????= h ρ g
h = height of liquid column in the tube
ρ = density of solution,
g = acceleration due to gravity.

10. Osmotic pressure(π) :-
The liquid column in the tube
creates hydro static pressure
that pushes the solvent back
through membrane in to
container.
When rate of forward and
reverse process is equal
equilibrium is established.
And the hight of liquid column
in the tube remain constant.

11. Isotonic, Hypertonic and Hypotonic solutions:
*Isotonic solutions –Two or more solutions having the same
osmotic pressure are said to be isotonic solutions. (or iso-osmotic
solutions)
E.g. 0.1M urea solution and 0.1M sucrose solution are isotonic,
??????
1= ??????
2respectively, with same molar(M) concentrations but
different concentrations in g/L.
If these solutions are separated by a semipermeable membrane,
there is no flow of solvent in either direction.

12. Hypotonic solutions–The more dilute solution with lower osmotic
pressure is said to be hypotonic solution.
e.g. If ??????of sucrose solution is higher than that of urea solution, the
urea solution is hypotonic to sucrose solution.
Hypertonic solutions –The more concentrated solution with
higher osmotic pressure is said to be hypertonic solution.
e.g. If ??????of sucrose solution is higher than that of urea solution,
the sucrose solution is hypertonic to urea solution.

14. Osmotic pressure and concentration of solution:
For dilute solutions, the osmotic pressure follows the equation,
-----(1)
V= volume of a solution in dm
3
n
2= moles of non volatile solute.
R=molar gas constant = 0.08206 dm
3
atm K
-1
mol
-1
??????= osmotic pressure in atm
??????
??????/ ??????= concentration in molarity (M)
??????= ??????
2????????????
V
??????= MRT

15. Molar mass of solute from osmotic pressure:
if mass of solute in V litresof solution is W
2
molar mass is M
2then n
2= W
2/M
2
??????= ??????
2????????????
V
??????= �
2????????????
??????
2�
??????
2 = �
2????????????
??????�

16. Reverse Osmosis:
.When the pressure larger than the
osmotic pressure of solution is
applied to solution, then pure
solvent from solution flows from
solution to pure solvent through
semipermeable membrane.
Reverse osmosis is used for the
desalination of sea water for getting
fresh drinking water

17. The figure shows fresh water and
salty water are separated by a
semipermeablemembrane.
When the pressure larger than the
osmotic pressureof solution is
applied to solution, pure water from
salty water passes into fresh pure
water through the membrane

18. Thank You