Osmosis is the flow of solvent from an area of higher solvent concentration to lower concentration. The equilibrium hydrostatic pressure resulting from osmosis is called osmotic pressure. There are three laws that govern osmotic pressure that are analogous to gas laws: 1) Boyle's law - osmotic pressure is proportional to concentration at constant temperature, 2) Charles' law - osmotic pressure is proportional to absolute temperature at constant concentration, 3) Avogadro's law - osmotic pressure is proportional to amount of solute. These laws allow derivation of an equation for osmotic pressure that is identical to the ideal gas law, indicating dilute solutions behave similarly to ideal gases.

3.  ‘’The flow of the solvent from higher concetration
to lower solvent concetration is called osmosis’’.

4. The equilibrium hydrostatic pressure of the
column set up as a result of osmosis is called
osmotic pressure.
1. Laws of osmotic pressure

5. A substance in the solution behaves exactly
like a gas and the osmotic pressure of a dilute
solution is equal to the pressure which the
solute would exert, if it were a gas at the
same temperature and occupying the same
volume as a solution.
This theory based on simple laws. Just like the
gas laws. These law are discussed as follows.

6. Vent Hoff-Boyle’s law:
i. ‘’According to this law, at a certain temperature, the
osmatic pressure of a solution is proporational to its molar
concentration.’’
 𝜋 ∝ C (at const. temperature)
 𝜋 = K.C. (at const. temperature)

𝜋
𝑐
= K (at const. temperature)
 𝜋V=k
Hence,
this is just like a bole law for gases according to which pv=
constant, at a constant temperature.

7.  “According to this law the osmatic pressure of a
solution is proportional to absolute temperature at
a given concentration.’’
𝜋 = T (When concentration is const.)
X = KT (When concentration is const.)
𝜋
𝑇
= K (When concentration is const.)
This is just like the pressure temperature law for gases.
𝑝
𝑇
= k

8.  In the above mentioned three laws, we have
been given the idea that:
 𝜋 ∝
1
𝑉
 𝜋 ∝ 𝑇
 𝜋 ∝ 𝑛
 If all these three parameter V, T and n vary
simultaneously, then
 𝜋 ∝
𝑛𝑇
𝑉

9.  𝜋 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
𝑛𝑇
𝑉
 𝜋𝑉 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑛𝑇
 The value of the constant determined by various
experiment is general gas constant “ R”.
 So 𝜋𝑉 = 𝑛𝑅𝑇
 This equation is identical to ideal gas equation
 PV = nRT
 It is found that the dilute solution behave just
like ideal gases.

10.  We have derived the general equation for solutions
as
𝜋𝑉 = 𝑛𝑅𝑇
𝜋 =
𝑛
𝑉
. RT
𝜋 = 𝐶. 𝑅𝑇
 AT constant temperature.
𝜋 ∝ 𝐶
It means that the osmotic pressure only depend upon
the concentration of the solution but not upon the
nature of solute. Hence, osmotic pressure is a
colligative property.