When a solid solute is added to the solvent like water , some solute dissolves and its concentration increases in solution . This proces is known as as ' dissolution ' . Some solute particles in solution collide with solid solute particles and get separated out of solution . This process is known as ' crystallisation '. A stage is reached when the ttwo processes occur at the same rate and thus a dynamic equilibrium is reached ,
..............................................Dissolution <-----------> crystallisation
Factors affecting the rate of dissolution :
(i) Effect of temperature -
The rate of dissolution of a solid in a liquid is significantly affected by temperature changes as the above dynamic equilibria must follow LeChatelier's Principle. In general , if the dissolution process is endothermic ( {tex}\Delta H{/tex} sol < 0 ) , the solubility increases with rise in temperature. and if it is exothermic ( {tex}\Delta H{/tex} sol > 0 ) the rate of dissolution decreases . These trends have been experimentally observed governing the concerned rate law too..
(ii) Effect of pressure -
Since both solids as well as liquids are highly incompressible , variations of pressure does not have any significant effect on tthe process or rate of dissolution of a solid in water.
Dr. Kamlapati Bhatt 6 years, 8 months ago
When a solid solute is added to the solvent like water , some solute dissolves and its concentration increases in solution . This proces is known as as ' dissolution ' . Some solute particles in solution collide with solid solute particles and get separated out of solution . This process is known as ' crystallisation '. A stage is reached when the ttwo processes occur at the same rate and thus a dynamic equilibrium is reached ,
..............................................Dissolution <-----------> crystallisation
Factors affecting the rate of dissolution :
(i) Effect of temperature -
The rate of dissolution of a solid in a liquid is significantly affected by temperature changes as the above dynamic equilibria must follow LeChatelier's Principle. In general , if the dissolution process is endothermic ( {tex}\Delta H{/tex} sol < 0 ) , the solubility increases with rise in temperature. and if it is exothermic ( {tex}\Delta H{/tex} sol > 0 ) the rate of dissolution decreases . These trends have been experimentally observed governing the concerned rate law too..
(ii) Effect of pressure -
Since both solids as well as liquids are highly incompressible , variations of pressure does not have any significant effect on tthe process or rate of dissolution of a solid in water.
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