1 . Definition of Solution : When two or more chemically non-reacting substances are mixed and form homogeneous mixture is called solution.
When the solution is composed of only two chemical substances, it is termed a binary solution, similarly, it is called ternary and quaternary if it is composed of three and four components respectively.
Solution = solute + solvent
♦ Solute : Generally the component present in lesser amount than other component in solution is called solute.
♦ Solvent : Generally, the component present in greater amount than any or all other components is called the solvent.
* Physical state of solvent and solution is same.
E x . In a syrup (liquid solution) containing 60% sugar (a solid) and 40% water (a liquid - same aggregation as solution), water is termed as the solvent.
2 . Dilute Solution : A solution in which relatively a small amount of solute is dissolved in large amount of solvent is called a dilute solution.
3 . Concentrated solution : A solution in which relatively a large amount of the solute is present is called a concentrated solution.
4 . Saturated solution : The maximum amount of solute in grams, that can be dissolved in 100 g of a solvent at a particular temperature is called solubility of the solute and such a solution is called saturated solution.
5 . Super saturated solution : A solution containing more amount of solute than that required for saturation of a given amount of solvent at a particular temperature, is called a supersaturated solution.
* It is unstable system.
6 . Types of Solution :
♦ Sp. Note : The solution of liquid in gas or solid in gas is not possible because the constituents can not form a homogeneous mixture.
7 . Properties of a solution :
(i) A solution consists of a single phase i.e. it is a monophasic system.
(ii) A solution is uniform throughout, so it has uniform properties such as density refractive index, etc.
(iii) Size of solute particles in a solution is of the order 10-7 — 10-8 cm.
(iv) The components of a solution can not be easily separated by physical methods.
(v) The properties of a solution are the properties of its components. i.e. the components do not lose their properties when they form a solution.
(vi) The composition of a solution is not definite but can vary within certain limits.
(vii) Certain properties of solution such as density, viscosity, surface tension, boiling point, freezing point etc.
vary with the composition of the solution.
