Factors Affecting Solubility

Have you ever made traditional medicine by dissolving salt in water to soothe a sore throat?  This in chemical reactions is called solubility.  Where, when mixed and stirred, the salt grains that were originally in the water will disappear and the taste will become salty.  In this salt solution, water is the solvent and salt is the solute.  In general, almost all compounds can be dissolved in certain solvents, be they ionic compounds (salt, acid) or non-ionic compounds (sugar).  

So what is solubility?  Solubility is the maximum possible concentration of a solute in a solution at a given temperature and pressure.  Solutes, namely substances that are dissolved in a solvent and are in less quantity than the solvent.  Meanwhile, a solvent is a substance used to dissolve a solute and the amount is greater than the dissolved substance.  Based on the amount of solute contained in the solvent, solutions are divided into three types, namely unsaturated solutions are solutions that contain less solute than saturated solutions.  Second, an exactly saturated solution is a solution that contains the maximum amount of substance that can dissolve in the solvent at a certain temperature.  Finally, a supersaturated solution, namely a solution that contains more solute than a saturated solution.  Substance Solubility Factors In general, the solubility of substances in solvents varies.  This depends on factors that influence solubility.

There are several factors that influence solubility, including;  temperature, type of solvent, pH, and the presence of similar (similar) ions

 a) Temperature

 The effect of temperature on solubility only has a significant effect if the reactant phase has a solid or gas phase.  For the solid phase, the higher the temperature, the higher the solubility of the solid in a solvent.  As the temperature of the solution increases, the distance between the molecules of the solid becomes looser.  This causes the bonds between solid substances to be easily separated by the attractive force of water molecules, so that the substances dissolve easily.

 b) Solvent Type

 A compound will dissolve if it has the same polarity level as the solvent.  The more similar the level of polarity between the solute and solvent, the higher the solubility of the solute in the solvent.

 c) pH

 The solubility of salts derived from weak acids depends on the solution.  For example, oxalic acid, when dissolved in water, will release H+ ions and C2O24- ions.  The H+ ions from the water will combine with the oxalate ions C2O24- forming oxalic acid again H2C2O4 thereby increasing the solubility of the salt.

 d) Presence of Similar Ions (similar ions)

 Electrolytes that consist of the same metal ions such as AgCI, AgNO3, Ag2CrO4, AgBr, and Ag3PO4 are said to have the same ion, namely the silver ion (Ag+).  Likewise, AgCI, NaCI, CaCI2, and AICI3 are also said to have a common ion, namely the chloride ion (Cl–).