Isotonic solution

Isotonic solution-

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Isotonic  or Iso – osmotic solutions-

Two solutions of different substances having same osmotic pressure at same temperature are called isotonic solutions. When isotonic solutions are separated by Semipermeable membrane , no osmosis takes place. Isotonic solutions have equal molar concentrations.

For isotonic solutions,

π_{1  =}   π2 

π₁ and π₂ are osmotic pressures.

C₁ = C₂ 

C₁ and  C₂ are molar concentrations 

                             [  C = n/V = no. of moles /volume of solution in litre  ]

n₁ /V₁ = n₂ /  V₂              [ n = w /m = weight of solute / molecular weight ]

w₁ / m₁ V₁ =    w₂ / m₂ V₂

These are applicable when there is no dissociation or association of solute takes place.

(i) In case of isotonic solution of  non electrolyte solutes  ( ex. isotonic solutions of urea and glucose ),

       π_{1  =}   π2 

         C₁ = C₂

(ii)In case of isotonic solution of urea (non electrolyte ) and NaCl (  electrolyte it dissociates in solution) ,                  

      π_{1  =}   π2 

       C₁ ≠ C₂

(iii) In case of isotonic solution of urea (non electrolyte ) and Benzoic acid (  electrolyte it associates in solution) ,

         π₁ =  π2 

          C₁  ≠ C₂

Hypotonic solution-

If a solution having less osmotic pressure than other is called hypotonic solution .

or

 Solution is hypotonic if it has less solute and more water than another solution.

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Hypertonic solution-

If a solution having more osmotic pressure than other is called hypertonic solution.

or 

When a solution has more solute per litre than another is called hypertonic solution.