buffer solution and it's types

A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solutionconsisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acidor base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood.

Principles of buffering

Buffer solutions achieve their resistance to pH change because of the presence of an equilibrium between the acid HA and its conjugate base A⁻. and only a little is consumed in the neutralization reaction which results in an increase in pH.

Predicting the pH of a Buffer. The pH of a buffer is determined by two factors; 

1) The equilibrium constant Ka of the weak acid and 2) the ratio of weak base [A^-] to weak acid [HA] 

in solution. ... When the concentrations of A^-and HA are equal, the concentration H⁺ is equal to K_a, (or equivalently pH = pK_a).

There are two types of buffer solutions, (i) Solutions of single substances: The solution of the salt of a weak acid and a weak base. (ii)Solutions of Mixtures: These are further of two types, (a) Acidic buffer : It is the solution of a mixture of a weak acid and a salt of this weak acid with a strong base.