GOVERNMENT ENGINEERING COLLEGE- BHARUCH 130140105050 YASH THUMAR 130140105012 HARDIK KALATHIYA 130140105013 PRATIK KATHIRIYA

OSMOTIC EQUILIBRIUM AND OSMOTIC PRESSSURE

OSMOSIS Diffusion of water through the semi permeable membrane from a solution of lower concentration towards a solution of higher concentration

Growth in a shoot tip wilting Fresh water trout Sea water Herring Turgid plant

Physics of Osmosis Water tends to flow from where its chemical potential is higher to where it is lower OR Movement of water from region where net hydrostatic pressure is higher to a region where it is low across a semi permeable membrane

Solute decreases chemical potential of water Solute decreases chemical potential of water. Reduced chemical potential causes reduced vapor pressure and thus higher boiling point of the solution as compared with pure water Movement of molecules from higher chemical potential to lower chemical potential is accompanied by a release of free energy. Osmosis releases energy and can be made to do work, as when a growing tree root splits a stone.

Osmotic Pressure and the factors on which it depends: Van’t Hoffs Equation All non penetrable solutes in a solution exerts osmotic pressure According to Van’t Hoff, osmotic pressure (π) depends on the molar concentration (C) of the solution and the temperature T π = R C T where R is the gas constant

Osmotic pressure Osmotic pressure is higher when molar concentration is higher or temperature is higher and the molecular weight is lower Osmotic pressure depends mainly on the molar concentration or molarity of a solution Osmotic pressure is a colligative property, meaning that the property depends on the concentration of the solute but not on its identity

The osmotic pressure of an ionic solution is π = i R C T where “i” is the number of ions formed by dissociation per molecule The greater the no of ion/molecule when dissolved greater the osmotic pressure

Pressures of a solution Osmotic pressure (the pulling pressure) of a solution is the measure of tendency of a solution to pull water into it by osmosis because of the relative concentration of non penetrating solute and water Hydrostatic pressure of a solution is the pressure exerted by a stationary fluidic part of the solution on an object (semi permeable membrane in case of osmosis) Net hydrostatic pressure of a solution = hydrostatic pressure –osmotic pressure

Example Separate pure water from a sugar solution with semi permeable membrane Both have same hydrostatic pressure Osmosis take water from side 1 to side 2 because solution on side 2 has greater pulling tendency

Osmosis: due to difference in net hydrostatic pressure The hydrostatic pressure of pure water is higher than that of solution on right

Will all water go to side 2? No it stops after some time. This is the equilibrium state

Equilibrium state As water moves by osmosis to side 2. Solution on side 2 has two tendencies now Tendency to push water back to side 1 due to greater hydrostatic pressure Tendency to pull water by osmosis back to side 2 Equilibrium is achieved when tendency to pull water to side 1 and to push water into side 2 balances out

Osmotic Equilibrium Osmotic equilibrium is the term used to indicate that the concentration of a solute in water is the same of both side of a semi permeable membrane. While the water still passes through the membrane, there is no gain or loss on either side.

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