Question

How many types of solutions are formed? Write briefly about each type with an example.

Answer 1

A homogeneous mixture means that its composition and properties are uniform throughout the mixture. The substances that make up the solution are called the components of the solution. Based on the total number of components present in a solution, it is called a binary solution (two components), ternary solution (three components), quaternary solution (four components), etc.

The components of a binary solution are usually called the solute and the solvent. Generally, the component present in the largest quantity is called the solvent, while the other component present in the smallest quantity is called the solute. The solvent determines the physical state in which the solution exists. In other words, the solute is the substance that dissolves and the solvent is the substance in which the solute dissolves.

For example, if some crystals of sugar are put in a beaker filled with water, they dissolve in the water and form a solution. In this case, sugar is the solute, and water is the solvent. The solution's particles have a molecular size of about 1000 pm, and no physical technique, such as filtration, decantation, centrifugation, etc., can separate its various components.

Types of Solutions: Depending upon the physical state of the solute and solvent, solutions may be classified into the following types:

Type of Solution	Solute	Solvent	Common Examples
Gaseous Solutions	Gas	Gas	mixture of oxygen and nitrogen gases
	Liquid	Gas	Chloroform mixed with nitrogen gas
	Solid	Gas	Camphor in nitrogen gas
Liquid Solutions	Gas	Liquid	Oxygen dissolved in water
	Liquid	Liquid	Ethanol dissolved in water
	Solid	Liquid	Glucose dissolved in water
Solid Solutions	Gas	Solid	Solution of hydrogen in palladium
	Liquid	Solid	Amalgam of mercury with sodium
	Solid	Solid	Copper dissolved in gold

Three of the nine types of solutions listed above are very common: solid in liquid, gas in liquid, and liquid in liquid. All three types of solutions have liquid as the solvent. Solutions that have water as the solvent are called aqueous solutions, while solutions that do not have water as the solvent are called non-aqueous solutions. Examples of common non-aqueous solvents are ether, benzene, carbon tetrachloride, etc.

The types of solutions are explained below:

1. Gaseous solution: A gaseous solution is a solution in which the solvent is a gas. In these solutions, the solute may be liquid, solid, or gaseous. For example, a mixture of oxygen and nitrogen gas is a gaseous solution.
2. Liquid solution: These solutions are formed by mixing solids or gases in liquids or by mixing two liquids. Some solid substances also form liquid solutions when mixed. For instance, mixing equimolar amounts of sodium and potassium metals at room temperature results in a liquid solution. Oxygen dissolved in water in sufficient quantity protects aquatic organisms in ponds, rivers and seas.
   1. When both the components are completely miscible: In this case, both the liquids are of a similar nature, i.e., either both are polar (e.g., ethyl, alcohol and water) or nonpolar (e.g., benzene and hexane).
   2. When both the components are almost miscible: Here, one liquid is polar, and the other is nonpolar in nature, e.g. benzene and water, oil and water, etc.
   3. When both the components are partially miscible: If the intermolecular attraction A-A in liquid A is different from the intermolecular attraction B-B in liquid B, but the A-B attraction is of intermediate order, then both the liquids are limitedly miscible with each other. For example, ether and water are partially mixed.
3. Solid solution: A solid solution is a solution in which the solvent is a solid. The solute may be gas, liquid or solid. For example, gold and copper form solid solutions because gold atoms replace copper atoms in copper crystals, and similarly, copper atoms can replace gold atoms in gold crystals. Alloys of two or more metals are solid solutions.
   Solid solutions can be divided into two classes –
   
   1. Substitutable solid solutions: In these solutions, atoms, molecules or ions of one substance replace the particles of the other substance in the crystal lattice. Brass, copper and zinc are common examples of substitutable solid solutions.
   2. Interstitial solid solutions: In these solutions, atoms of one type occupy the vacancies or gaps present in the lattice of atoms of the other substance. A common example of an interstitial solid solution is tungsten carbide (WC).