2. Solutions Class 12 Chemistry Chapter 2 Solutions, Class 12 Chemistry | Page 14

o For instance , solids like naphthalene and anthracene do not dissolve in water but dissolves easily in benzene but sugar and salt does not dissolves in benzene .
o This is because it is property of solution that polar solutes dissolve in polar solvents like Water , ethanol , formaldehyde and chloroform whereas non polar solutes in nonpolar solvents like pyridine , toluene , and hexane . This phenomenon can be easily defined as like dissolves like . o
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The phenomenon of increase in the concentration of solution due to dissolving of solid solute to the solvent is known as dissolution .
The phenomenon of collision of solute particles in a solution resulting in the separation of the solute particles from the solution is known as crystallization .
A phase when number of solute particles going into solution is equal to the solute particles separating out of the solution is known as equilibrium . The concentration of solute remains constant at this stage .
A solution in which no more solute can be dissolved into the solvent at the same temperature and pressure is known as saturated solution .
Whereas a solution in which more solute can be dissolved in the solvent at the same temperature and pressure is known as unsaturated solution .
According to Le Chateliers Principle in a saturated solution , if the dissolution process is endothermic ( Δsol H > 0 ), the solubility should increase with rise in temperature but if the dissolution process is exothermic ( Δsol H > 0 ) the solubility should decrease .
Pressure does not have crucial effect on solubility of solids in liquids because they remain unaffected to pressure due to the high incompressibility of solids and liquids .