Question

Define solubility and write the factors which influence the solubility.

Answer 1

Hint: Property of a solute-solvent interaction used to define for a fixed concentration of solute in solution, and its interaction in the equilibrium. Different factors affect equilibrium of solubility.

Complete answer:
Solubility may be defined as the upper limit of solute that could be dissolved in a given amount of solvent at equilibrium. In such a type of equilibrium, Le chatelier’s principle can be used to explain most of the main factors that affect solubility. Le Chatelier’s principle helps to predict what effect a change in temperature, concentration or pressure will have on the position of the equilibrium in a chemical reaction.
Solubility is the amount of solute (in grams or in moles) that can be dissolved in 100 grams of a solvent to get a saturated solution at a particular temperature.
Factors affecting solubility are:
(1) Solute solvent interactions: Nature and relation of solute and solvent affect solubility to a great extent. Strong solute-solvent interactions give greater solubility while weak solute-solvent interactions give lesser solubility. In the same way, polar solutes tend to dissolve best in polar solvents and nonpolar solutes tend to dissolve in nonpolar solvents. Common ion effect is a term that tells that the decrease in solubility of an ionic compound when a salt that contains an ion that already exists in the chemical equilibrium is added to the mixture.
(2) Temperature: Effect of temperature on the solubility differs depending upon whether the reaction is exothermic or endothermic. For solids, in endothermic reaction, solubility increases with increase in temperature, and in exothermic reaction, solubility decreases with increase in temperature. For gases, dissolving gas is usually in exothermic reactions, increasing temperature lowers solubility, and decreasing temperature increases solubility.
(3) Pressure: the effect of pressure on solubility of gases in liquids can be described through Henry’s law and Le chatelier principle. According to Henry’s law,when temperature is constant, the solubility of gas corresponds to its partial pressure. When partial pressure of gas decreases, the concentration of gas in the solution also decreases, hence solubility decreases.

Note: In the case of liquids, there are no defined trends for the effects of temperature on the solubility of liquids. Effect of pressure changes on liquids and solids are negligible.Though in small amounts, particle size also affects solubility. Smaller the size, larger the surface area, large surface area allowed greater interaction with solvent resulting in greater solubility.