osmotic pressure
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Welcome to My Presentation
OSMOTIC PRESSURE
Course Title: Physical Chemistry IICourse Code: ACCE 260Applied Chemistry & Chemical Engineering
SHAIKH ASHRAFUL ALAM Dept. of Applied Chemistry & Chemical Engineering BSMRSTU,Gopalgang,Bangladesh
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
Osmotic PressureOsmotic pressure is the minimum pressure which needs to be applied
to a solution to prevent interior flow of water across a semipermeable membrane.
orThe pressure required to stop osmosis.
Osmosis and Osmotic Pressure
Determination of Osmotic Pressure
Pfeffer’s MethodBerkely and Harthey’s MethodA Modern Osmometer.
Important term of osmosis & Osmotic pressureIsotonic: 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
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 ( here is osmotic pressure)
Calculating osmotic pressure
The ideal gas law states
But n/V = M and so
Where is the molar concentration of particles and is the osmotic pressure, isVan’t Hoff factor
𝑃𝑉=𝑛𝑅𝑇𝜋=𝑖𝑀𝑅𝑇
Relation between osmatic pressure and other colligative properties
Here, is the elevation in the boiling or depression in the freezing point. is the boiling or freezing point of the solvent. is the enthalpy change during phase change. is the mole fraction of solute in solution.
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
Importance of Osmosis and Osmotic Pressure
Oncotic pressure of blood plasma
Formation of tissue fluid
Regulation of cell volume
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