Why do different substances have different solubilities?

Because different elements have a range of electronegativities, and because there are infinite kinds of molecular geometries, there is tremendous variation in molecular polarity across different molecule types. As a result, the degree of solubility varies tremendously across compounds.

Since each substance is composed of different atoms in different arrangements, and bonded together in different ways, each substance interacts with water in its own way and has its own characteristic solubility.

That’s partly due to the fact that The ions in sodium chloride, Na⁺ And Cl-, have lower charges than the ions in calcium carbonate, Ca²⁺ And CO₃^2–. The higher the charges on the ions, the stronger their electrostatic attraction for each other, and the harder it is for the water to pull them apart.

This point of maximum concentration, the saturation point, Depends on the temperature of the liquid as well as the chemical nature of the substances involved.

It has been observed that Solid solubility depends on the nature of the solute as well as the solvent. We often see that substances like sugar, common salt (NaCl), etc readily dissolve in water while substances like naphthalene do not dissolve in water.

Solubility is affected by 4 factors – Temperature, pressure, polarity, and molecular size. Solubility increases with temperature for most solids dissolved in liquid water. This is because higher temperatures increase the vibration or kinetic energy of the solute molecules.

The size of solute particles, stirring, and temperature, are the three factors that affect the solubility of a solid solute in a solvent.

In general, the solubility of a substance depends on not only the energetic factors we have discussed but also the temperature and, for gases, the pressure. At 20°C, for example, 177 g of NaI, 91.2 g of NaBr, 35.9 g of NaCl, and only 4.1 g of NaF dissolve in 100 g of water.

Substances with similar polarities tend to be soluble in one another (“like dissolves like”). Nonpolar substances are generally more soluble in nonpolar solvents, while polar and ionic substances are generally more soluble in polar solvents.

The solution is said to be saturated if The rate of crystallization and the rate of solubility are the same.

Saturation Depends on the Solute

As you can see from the graph, solutes vary greatly in how soluble they are in water. For example, you can dissolve almost 20 times as much sugar as baking soda in the same amount of water at this temperature.

Based on the chemical properties of both the solvent and the solute, the degrees to which a solute will dissolve in a solvent vary. The amount of solute that can dissolve in any given solvent depends on the temperature, volume or mass ratio, and other chemical properties of the substances.

Strong solute-solvent attractions equate to greater solubility while weak solute-solvent attractions equate to lesser solubility. In turn, polar solutes tend to dissolve best in polar solvents while non-polar solutes tend to dissolve best in non-polar solvents.

Substances with similar polarities tend to be soluble in one another (“like dissolves like”). Nonpolar substances are generally more soluble in nonpolar solvents, while polar and ionic substances are generally more soluble in polar solvents.

Drug solubility depends on the PH of fluid, temperature, volume, and contents of fluid. The lipophilicity of a drug is also correlated with water solubility. The rate and extent of absorption can be altered by food.

Solubility is the amount of solute that can dissolve in a given amount of solvent at a given temperature. Some solutes have greater solubility than others. Temperature affects the solubility of solutes in all three states. Pressure also affects the solubility of gases.