Osmotic pressure. 📚

 *Semipermeable membrane:

                                 It is membrane which allows the solvent molecule and not the  solute molecules,  to pass through it.



*Osmosis: 

                               The spontaneous and unidirectional flow of solvent molecules through semi permeable membrane,  into the solution of lower concentration to the higher concentration it is called osmosis. 


                                                                             
*Osmotic pressure:

           The excess pressure on the side of the solution that stops the net flow of solvent into solution through semipermeable membrane is called osmotic pressure. 


* There are 3 types of solutions:

1.Isotonic solution:

                 Two or more solution exerting the same osmotic pressure are called isotonic solution. 

Eg.0.05m urea solution and 0.05m sucrose solution. 

2.Hypertonic solution:

                       A solution having osmotic pressure higher than that of another solution is said to be hypertonic solution.

3.Hypotonic solution:

                   A solution having osmotic pressure lower than that of another solution is said to be hypotonic solution. 



* Osmotic pressure and concentration of solution :

     For every dilute solution, the osmotic pressure follows the equation 

pie= n2RT÷ V

Where, V is volume of solution ,n2 is moles of nonvolatile solute,R is gas constant and pie is osmotic pressure. 

We know that  n2÷V=M

Therefore,  pie=MRT



*Molar mass of solute from osmotic pressure:

We know that 

Pie= n2RT÷ V

If W2 is mass of solution dissolved in V liters of solution and M2 be its molar mass.

Number of moles of a solute is given by

Pie= n2RT÷ V

n2=W2÷M2

Pie=W2RT÷ M2V     or    M2=W2RT÷pieV


*Reverse osmosis: 

                The pure solvent flows from solution into pure solvent through semipermeable membrane. This phenomenon  is called reverse osmosis. 


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