Solubility Curve

Solubility Rules Chart

Solubility is known as the maximum amount of solute which will dissolve in a given amount of solvent at a specific given temperature and pressure. There are three different kinds of solutions which will result depending on how much amount of a particular solute is dissolved in the solvent. A solubility curve refers to a data-based graph that compares the amount of solute which will dissolve in a given amount of solvent at different temperatures. The most typical solubility curves are the ones that are graphed based solid and gaseous solutes that are dissolved in 100 grams of water. In today’s article, we will learn about the solubility curve in detail which includes the solubility rules chart, solubility curve definition, solubility graph, some solubility curve problems, and the importance of solubility curve.

Solubility Curve Definition

The solubility curve definition chemistry is given as below:

The variation in the solubility of a given substance with the change of temperature is presented by the solubility curve. The solubility curve is the curved line that is drawn on the graph that shows the relationship between the temperature and the solubility of the substance at varying temperatures.

The graphical relationship between the solubility and the temperature is known as the solubility curve. The solubility curve determines the changes of the solubility of a solid at variable temperatures in a solvent. On the graph, the variations in temperature are to be plotted on the x-axis and the solubility is plotted on the y-axis. Temperature plays an important role in the solubility since the solubility of a given substance is different at varying temperatures.

Solubility Graph

Let us now look at how at the solubility graph looks like. The solubility graph is shown as follows:

(Image to be added soon)

Solubility Rules Chart

The general rules of solubility are given below. Let us look at each one of them and what they are.

  1. Most of the chloride salts are soluble. However, there are some exceptions like PbCl2, Hg2Cl2 and AgCl .

  2. The salts of Na+, K+ and NH4+ are all soluble.

  3. All the sulfate salts are soluble. However, there are some exceptions which include BaSO4, CaSO4 and PbSO4.

  4. Almost all the nitrate (NO3-) salts are soluble.

  5. Almost all the hydroxide compounds are hardly soluble. The important exceptions in this category are NaOH and KOH. Barium hydroxide and calcium hydroxide, however, are moderately soluble.

  6. All the salts of sulfide, phosphate and carbonate are hardly soluble.

Importance of Solubility Curve

The solubility curve is used for determining the amount of substance that is deposited when the solution is cooled. Solubilities of different substances at a given temperature can be determined. The importance of solubility curve is discussed as follows.

  1. The solubility of a substance at a given temperature is easily determined.

  2. The solubility process of any given substance at a given temperature is easily determined.

  3. The solubility curve helps in predicting which substance would crystallize out first from a solution that consists of two or more solutes.

  4. The solubility curve helps in comparing the solubilities of different substances at the same given temperature.

  5. The solubility curve brings a change in the solute composition substance.

  6. It gives you a clear idea of the fact that the solubility of a given substance changes with the temperature.

Solubility Curve Problems

Let us now look at some of the solubility curve problems in detail and how to solve them.


A solution with a precipitate of AgCl in equilibrium consists of 1.0 x 10-3mol of Ag+/ L and 1.3 x 10-5 mol of Cl-/ L. determine the solubility product of AgCl.


The solubility product as per the definition is the product of the concentrations of the ions that are in equilibrium with the precipitate of a sparingly soluble substance.

For AgCl,

Ksp = [ Ag+] [Cl-]

= ( 1.0 x 10-3 ) ( 1.3 x 10-5)

= 1.3 x 10-15

FAQ (Frequently Asked Questions)

1. What are Some Examples of Solubility?

Solubility is defined as the amount of the solute that will dissolve in a particular amount of a solvent. Most solutes tend to vary with different solvents. For example, most solids and liquids increase in their solubility at higher temperatures, but in the same given situation, gases tend to decrease in their solubility. However, drinks such as soda are bottled under pressure since gases are more soluble in this gaseous state. When the pressure is released by a person opening the container, the carbon dioxide immediately starts to lose its solubility and begins to escape. Based on these properties, you can say that there are several examples of solubility. Salt, for example, is highly soluble in water, but it is not soluble in oil. It is possible for you to add both cream and sugar to coffee since they both are soluble in the drink. Another example of solubility lies in the air that oxygen is soluble in nitrogen.

2. What Do You Mean By Solubility Product?

The solubility product of a substance which is denoted by Ksp is the ratio of the concentrations at equilibrium. Molar solubility, which is directly proportional to the solubility product, is the number of moles of the solute which dissolved per litre of the solution before the solution is saturated. Once the solution is saturated, any additional solute added precipitates out of the solution. The units of the solubility product are molarity (M), or mole per litre (mol/L).