关于溶解度-离子浓度曲线
Solubility-Ion Concentration Curve
Solubility is the property of a solid, liquid, or gaseous and is the amount of space a substance takes up. The higher the space, the higher the solubility of the substance. A solubility-ion concentration curve is a graphical representation of this concept demonstrating how solubility is affected by increased ion concentration.
In solubility-ion concentration curves, the x-axis is generally ion concentration and the y-axis is solubility. The concentration of ions in a solution affects solubility in two primary ways. Firstly, it may alter the interactions between a solute and a solvent; an increase in the concentration of a specific ion may decrease the amount of that specific ion of the same charge so that interactions with the solvent weakens and non-electrostatic interactions can predominate. Secondly, increased ion concentration may reduce solubility due to the increase of solute-solute interactions.
In general, increasing ion concentration increases the solubility of highly ionized (or ionizable) solutes such as salts, acids and bases. A classic example is the solubility of ammonium chloride in water. At low concentrations the dominant forces are hydrogen bonding between the ammonium ions and the water molecules, leading to an observed increase in solubility. As the concentration of the ammonium chloride increases, the dominant force is the attractive force between the two molecules in the salt which reduces the amount of energy needed to separate the molecules. This leads to a decrease in solubility.
The solubility-ion concentration curve is also affected by the type of ions in solution. For example, the solubility of sodium chloride will increase with increasing concentration because of the combination of increased ion-dipole interactions and increased ion-ion interactions. The salt will be less soluble in the presence of other ions, such as potassium chloride, which can produce a decrease in the solubility of sodium chloride due to the formation of an ion-complex between the two ions.
The solubility-ion concentration curve also depends on the properties of the solute and solvent. Some solvents, such as water, are polar and are capable of forming strong hydrogen bonds with certain types of ions, leading to an increase in solubility. In the case of non-polar solvents, such as oils, the forces of attraction between solute and solvent particles are van der Waals forces and London dispersion forces, which are weaker than hydrogen bonds and result in lower solubility.
In conclusion, the solubility-ion concentration curve is a very useful tool in understanding how solubility is affected by increased ion concentration. The shape of the curve depends on the type of ion, the nature of the solvent, and the strength of the electrostatic interactions between the ion and the solvent; increasing the ion concentration can lead to an increase or decrease in solubility depending on the interactions present in the solution.
