Solubility

The maximum amount of solute that can dissolve in a known quantity of solvent at a certain temperature is its solubility.


A solution is a homogeneous mixture of one or more solutes in a solvent. Sugar cubes added to a cup of tea or coffee is a common example of a solution. The property which helps sugar molecules to dissolve is known as solubility. Hence, the term solubility can be defined as a property of a substance (solute) to dissolve in a given solvent. A solute is any constituent which can be either solid or liquid or gas liquified in a solvent.

Solubility Product

The term solubility product is generally applicable for frugally soluble salts. It is the maximum product of the molar concentration of the ions (raised to their appropriate powers) which are produced due to dissociation of the compound.


At a given temperature the solubility product is constant. Lesser the value of solubility product indicates lower solubility and higher value of solubility product indicates greater solubility.


Solubility Definition

Solubility is a property referring to the ability for a given substance, the solute, to dissolve in a solvent.It is restrained in terms of the maximum amount of solute dissolved in a solvent at balance. The resulting solution is called a saturated solution. Certain substances are soluble in all proportions with a given solvent, such as ethanol in water. This property is known as miscibility.Under numerous conditions, the balance solubility can be surpassed to give a so-called supersaturated solution, which is metastable.The solvent is frequently a solid, which can be a clean substance or a mixture.

  • Solubility of Gases In Liquids

Gas solubility in liquids involves the concept of gas dissolving in a solvent. Let us first define solubility. For any substance, solubility is the maximum amount of solute that can be dissolved in a given solvent at a particular temperature. Now our concern is gas solubility in liquids. The gas solubility in liquids is significantly affected by temperature and pressure and also by the nature of the solute and the solvent.


(image will be uploaded soon)


There are many gases that readily dissolve in water, while there are gases that do not dissolve in water under normal conditions. Oxygen is just sparingly soluble in water whereas HCl or ammonia readily dissolves in water.


Other Types of Solubility

  • Solubility of Liquids In Liquids

Water is known as a universal solvent as it dissolves almost every solute except for a few. A few factors can influence the solubility of a substance.


Solubility is the new bond formation amongst the solute molecules and solvent molecules. In terms of quantity, solubility is the maximum concentration of solute that dissolves in a known concentration of solvent at a given temperature. Based on the concentration of solute dissolves in a solvent, solutes are categorized into highly soluble, sparingly soluble or insoluble. If a concentration of 0.1 g or more of a solute can be dissolved in a 100ml solvent, it is said to be soluble. While a concentration below 0.1 g is dissolved in the solvent is known to be sparingly soluble. Thus, it is known that solubility is a quantitative expression and articulated by the unit gram/litre (g/L).


Based on solubility, different types of solution can be obtained. A saturated solution is a solution where a given amount of solute is completely soluble in a solvent at a given temperature. On the other hand, a supersaturated solution is those where solute starts salting out or precipitates after a particular concentration is dissolved at the same temperature.


Factors Affecting Solubility:

The solubility of a substance hinges on the physical and chemical properties of that element. In addition to this, there are a few conditions which can manipulate it. Temperature, pressure and the kind of bond and forces in between the particles are a few among them.

  • Effect of Temperature on Solubility: 

By changing the temperature we can increase the soluble property of a solute. Generally, water dissolves solutes at 20° C or 100° C. Sparingly soluble solid or liquid substances can be liquified completely by raising the temperature. But in the case of gaseous substance, temperature inversely influences solubility i.e. as the temperature increases gases expand and escape from their solvent.

  • Forces and Bonds:

Like dissolves in like. The type of intermolecular forces and bonds vary among each molecule. The chances of solubility between two dissimilar elements are more challengeable than the like substances. For example, water is a polar solvent where a polar solute like ethanol is easily soluble.

  • Pressure:

Gaseous substances are much more influenced than solids and liquids by pressure. When the partial pressure of gas rises, the chance of its solubility is also hiked. A soda bottle is an example of where CO2 is bottled under high pressure.


  • Solubility of Solids In Liquids

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

FAQ (Frequently Asked Questions)

1. How is Solubility Related to Concentration Why is it Important to Know the Solubility of a Substance?

Solubility is the amount of solute that can dissolve in a given amount of solvent at a given temperature. The concentration of a solution is the amount of solute in a given amount of solution. A dilute solution has a low concentration of solute. The measure of solubility determines how substances dissolve into one another. The substance dissolving into the other is the solute and the substance being dissolved into is the solvent. These factors can accelerate the rate of solubility or they can prevent certain substances from being soluble.

2. What is the KSP Formula and What are the Factors that Affect Solubility?

In general, MXb(s) ⇔ aM+b(aq) + bX-a(aq) is expressed as Ksp = [M+b]a[X−a]b. These expressions are called solubility product constant expressions because they involve the product of the equilibrium concentrations of the constituent ions, each raised to the power corresponding to the number of ions in the formula. Factors affecting solubility

  • Temperature. Basically, solubility increases with temperature. 

  • Polarity. In most cases solutes dissolve in solvents that have a similar polarity. 

  • Pressure. Solid and liquid solutes. 

  • Molecular size. 

  • Stirring increases the speed of dissolving.