Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the physical and chemical properties of the used solute and solvent as well as on temperature, pressure and the pH of the solution. The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration, where adding more solute does not increase the concentration of the solution and begin to precipitate the excess amount of solute.
Solution is a homogenous mixture of two or more substances in which at a constant temperature the amounts of solute and solvent can change up to a definite limit. For example- solution of salt in water, solution of sugar in water etc.
Micro-level classification of solution
- Dispersion: It is that constituent particles (molecule, atom or ion) which is scattered around the substance. Here also the first substance is called dispersed substance and second substance is called dispersive medium or medium of dispersion. After the phenomena of dispersion two types of substances are formed –Heterogeneous substance like suspension, colloid and true solution are different; Homogenous substances like true solution. The sizes of dispersed particles in suspension, colloid and true solution are different.
- Suspension: It is that substance (little size particle) which is insoluble in solvent but are visible through naked eye. The little particles can be filtered and these temporary which have a common tendency to scatter from the medium of dispersion. There are number of examples of suspension in our surrounding such as polluted water of river, smoke in the atmosphere etc.
- Colloid or colloidal solution: It is heterogeneous mixture of two substances the order of the sizes of the dispersed particles lie between 10-5 cm to 10-7. These dispersed particles cannot be seen through naked eye but can be seen through ultra-microscope and also cannot be filtered by blotting paper. For example- milk, gem, blood, ink etc.
- True solution: It is homogenous mixture of two or more substances and the dispersed particles have the molecular order of the range of the size 10-8. For example - solution of sugar in water, solution of ordinary salt in water etc.
- Neutral, Acidic and Alkaline solution: Neutral Solution is that solution in which the concentration of hydrogen ions (H+) is equal to the hydroxide ions (OH-). But the concentration of hydrogen ions (H+) is more than hydroxide ions (OH-) are called acidic solution while the solution in which the concentration of hydroxide ions (OH-) is more than hydrogen ions (H+) is called alkaline solution.
Characteristics of solution
- It is homogenous mixture of two or more substances and in any solution the radius of solute particles is very microscopic or more than microscopic that’s why these particles cannot be seen through microscope.
- Solute and solvent particles are diffuse such as that they cannot be distinguished.
- The solute particles presents in the solution cannot be filtered through the blotting paper.
- The solution is permanent and transparent.
Components of Solution
There are two types of components presents in the solution which are discussed below:
- Solute: It is the substance which is presented in the solution in lesser amount.
- Solvent: It is the substance which is presented in the solution in larger amount. The solvent which has dielectric constant is better solvent. The value of dielectric constant of the water is large that’s why it is called universal solvent.
Composition of solution
- Solution of gas: Air, the mixture of gases.
- Solution of liquid in gas: Solution of gases like Br, CO2, NH3 etc in water, cloud, mist, fog etc.
- Solution of solid in gas: Solution of iodine in air, smoke etc.
- Solution of gas in liquid: Solution of CO2 in water (H2O), solution of HCL gas in benzene (C6H6) etc.
- Solution of liquid in liquid: Solution of alcohol in water, solution of bromine in carbon disulphide, solution of H2SO4 in water etc.
- Solution of solid in liquid: Solution of sugar in water, solution of iodine in carbon tetrachloride, solution of lead in mercury, starch, gel, protein etc.
- Solution of gas in solid: Solution of hydrogen in Palladium metal, solution of camphor in air etc.
- Solution of liquid in solid: Solution of mercury in thallium, solution of water in sugar, solution of water in sugar, solution of water in salt etc.
- Solution of solid in solid: Zinc in copper, tin copper, aluminium in copper, solution (alloys) of zinc and nickel in copper.