Presentation about impotent term, OSMOTIC PRESSURE

1. Welcome
to
My Presentation

2. OSMOTIC PRESSURE
CourseTitle: Physical
Chemistry II
Course Code: ACCE 260
Applied Chemistry & Chemical
Engineering

3. SHAIKH ASHRAFUL ALAM
Dept. of Applied Chemistry & Chemical Engineering
BSMRSTU,Gopalgang,Bangladesh

4. Osmosis
The passage of solvent into solution or from more dilute to concentrated solution
when the two are separated from each other by a semipermeable membrane is
known as osmosis.
Diffusion of water through the semi permeable membrane from a solution of
lower concentration towards a solution of higher concentration
Pure Solvent
Concentrated
Solution
semi permeable
membrane
Solvent molecule
Solute molecule

5. Osmotic Pressure
Osmotic pressure is the minimum pressure which needs to be applied
to a solution to prevent interior flow of water across a semipermeable
membrane.
or
The pressure required to stop osmosis.

6. Osmosis and Osmotic Pressure

7. Determination of Osmotic Pressure
Pfeffer’s Method
Berkely and Harthey’s Method
A Modern Osmometer.

8. Important term of osmosis & Osmotic
pressure
Isotonic: Solutions have equal concentration of solute, and so equal osmotic
pressure.
Hypertonic: Solution with higher concentration of solute.
Hypotonic: Solution with lower concentration of solute.
Isotonic Hypertonic Hypotonic

9. Law of osmotic pressure
Boyle-van’t Hoff law for solutions
Charles’- Van’t Hoff law for solution
Combination of two law we get Van’t Hoff law for solution
π𝑉 = 𝑛𝑅𝑇 ( here 𝜋 is osmotic pressure)

10. Calculating osmotic pressure
The ideal gas law states
But n/V = M and so
Where 𝑀 is the molar concentration of particles
and 𝜋 is the osmotic pressure, 𝑖 isVan’t Hoff
factor
𝑃𝑉 = 𝑛𝑅𝑇
𝜋 = 𝑖𝑀𝑅𝑇

11. Relation between osmatic pressure and
other colligative properties
∆𝑇𝑖 =
(𝑅𝑇𝑖)2
∆𝐻𝑖
×
𝑛2
𝑛1 + 𝑛2
=
(𝑅𝑇 𝑖)2
∆𝐻 𝑖
× 𝑥2
Here,
∆𝑇𝑖 is the elevation in the boiling or depression in the freezing point.
𝑇𝑖 is the boiling or freezing point of the solvent.
∆𝐻𝑖 is the enthalpy change during phase change.
𝑥2 is the mole fraction of solute in solution.

12. Osmotic Pressure – Applications:
• Osmotic pressure effects normally move solvent molecules from a dilute to a concentrated
solution. In water desalination a large “external” pressure is used to push solvent molecules
(water) from sea water through a membrane to produce drinking water. The process is shown
below.
Desalination of saltwater by reverse osmosis

13. Importance of Osmosis and Osmotic Pressure
Oncotic pressure of blood plasma
Formation of tissue fluid
Regulation of cell volume