How to Find Out What Is Not Soluble in Water?

Based on what is not soluble in water, students, scientists and others have to take a decision for educational, research and commercial applications. If a particular chemical or solid is not soluble in water, it is easy to separate it out even if the solid will fall in the water. Solids which are soluble in water should be stored carefully, since it will be difficult to recover the material after it dissolves. The solubility of a particular material depends to a great extent on the chemical composition. A comprehensive explanation on how to find out materials which are not soluble are provided below.

Defining solubility

The solubility of a particular salt or chemical in water is defined in terms of moles per liter. If the concentration of the salt is more than 0.1 moles per liter at room temperature the salt is considered soluble in water. If the salt concentration in water at room temperature is less than 0.001 Moles/liter the salt is not soluble in water. In some cases the concentration of the salt will vary between 0.001 moles to 0.1 moles per liter and these salts are considered slightly soluble. The solubility also depends on other factors which are discussed below.

Process of dissolving

In case of soluble solids like salt or sugar, the intermolecular bonds between the molecules are comparatively weak. When these solids are added to water, the polar water molecules form a bond with the polar soluble solid molecules. In this process energy is released and it is sufficient to break the intermolecular bonds between molecules of the solid. The bonds are formed between the molecules of soluble chemical and the solvent. The amount of solid material which dissolves in one liter varies depending on the chemical composition. There is usually a limit of the amount of chemical which will dissolve in one liter. The maximum amount of solid corresponds to the saturation point.

Factors affecting solubility

In addition to chemical composition, one of the factors which affect the solubility is the temperature of the water. Usually most salts will dissolve quickly in water at a higher temperature, since there is more energy for breaking the intermolecular bonds in the salt. If the solid particles are small in size, there are fewer intermolecular bonds which have to be broken, so the salt will dissolve earlier. Also stirring will increase the energy in the water, making it is easier to break the intermolecular bonds, so the solid will dissolve faster. So at a low temperature, more salts will not be soluble in water.

What is not soluble in water.

The main factor which affects the solubility is the chemical composition since some chemicals have a structure which makes it easier to form a bond with the water molecules while others do not form a bond. Most sulphides, oxides, carbonates, chromates, phosphates and hydroxides of metals are not soluble in water since the molecules do not easily form a bond with the water molecules. Salts of Copper, silver, mercury, lead with chlorides, Iodides and Bromides are also not soluble though there may be some exceptions.

Some of the sulfate salts like barium sulfate, strontium sulphate, lead sulphate are not water soluble. Additionally calcium sulfate, silver sulfate, mercury sulfate are only slightly soluble in water.

Exceptions

However, it is observed that there are differences in solubility of these compounds for some of the metals and ammonium salts. Most of the salts of sodium, potassium and ammonium with chlorides, nitrates, sulfates and others are soluble.

How to find What is insoluble in water

Often a student or others wish to find out What is not soluble in water so that they can take suitable precautions while handling and storing it. The easiest way to find whether a particular material is not water soluble is by checking its chemical composition. In some cases, the chemical composition of the solid is not provided. In these cases, the user should add a small amount of the material to a transparent jar or beaker filled with water. If the material is not water-soluble, the solution may become cloudy initially when the solid is added. However, after some time, the solid will settle at the bottom of the container and the water will be clear, there is no change in the color, chemical properties of the water.