what is the effect of temperature on solubility of a solid in a liquid
Answers
Explanation:
The solubility of solutes is dependent on temperature. When a solid dissolves in a liquid, a change in the physical state of the solid analogous to melting takes place. Heat is required to break the bonds holding the molecules in the solid together. At the same time, heat is given off during the formation of new solute -- solvent bonds.
In general terms most compounds that dissolve in a liquid absorb heat that reflects the (endothermic) energy required to dismember the crystal lattice and the energy associated with solvation of each solute molecule. The amounts are thermodynamic quantities known as the heat of solution for the solvent-solute system.
On the basis of the le Chatelier principle - which predicts that any physical constraint imposed on a system in equilibrium will readjust to remove that constraint - any absorption of heat during the solubilisation process will respond to heat input by increasing both the rate of solubilisation and the concentration at saturation.
Occasionally anomalies occur due to the formation of different hydrates during the solubilisation process; eg, CaCl2 forms four different hydrates (1, 2, 4 and 6 water molecules per molecule of CaCl2) that affect the rate of dissolution as each hydrate is formed at various concentrations in the solubilisation process.
A further factor in determining the rate of solubilisation is the concentration gradient between the liquid solvent interface and the solute. To maximise the gradient and, therefore, the rate of solubilisation means stirring and maintaining agitation until saturation is achieved.