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How does the change in temperatue affectthe solubility of a solute in a liquid solvent and gaseous solute in liquid solvent ? Explain |
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Answer» Solution :Solid solute in liquid solvent: Genrally ,the solubility of a solid solute in a liquid solvent increases with increases in temperature ,when the temperature is increased the average kinetic energy of the molecules of the solute and the solvent increase . The increase in kinetic energy facilitates the solvent molecules to break the intermolecular attractive forces that keep the solute molecules together and hence the solubility increases When a solid is added to a solvent it begins to dissolve . (i.e) the solute leaves from the solidstate (dissolution ) .After some time some of the dissolved solute returns back to the solid state (RECRYSTALLISATION ) .If there is excess of solid present the rate of both these processes becomes equal ata particular stage. At this stage an equilibrium is established between the solid solute molecules and dissolved solutemolecules Solute (solid )` rArr ` Solute (dissolved) According to Le-Chatelier principle if the dissolution process is endothermine the increase in temperature will shift the equilibrium towards right (i.e.) Solubility increase . For an exotermic reaction the increase in temperature DECREASES the solubility .The solubilities of ammonium nitrate . calciumchloride, ceric sulphate nano-hydrate and SODIUM CHLORIDE in water at different temperatures are given in the following graph. Gaseous solute in liquid solvent: In the case of gaseous solute in liquid solvent ,the solubility decreases with increase in temperatures . When a gaseous solute dissolves in a liquid solvent its molecules interact with solvent molecules with weak intermolecular forces , When the temperatures increases ,the average kinetic energy of the molecules present in the solution also increases. The increases in kinetic energy breaksthe weak intermolecular forces between teh gaseous solute and liquid solvent which results in the release of the dissolved gas molecules to the gaseous state. Moreover ,the dissolution of most of the gases in liquid solvents is an exothermic process and in such processes ,the increase in temperature decreases the dissolution of gaseous molecules. |
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