Lakhasly

uffer solution (buffer system) is a solution that keeps pH at approximately the same level after the addition of small amount of strong acid or strong base.For example, for HF dissociation at a given temperature Kdiss is constant, the concentration is equal to "C", the degree of dissociation is equal to "?". HF <-> H+ + F- If the fraction of HF molecules that really dissociated is equal to ?, then the concentration of H+ is equal to C??, and the concentration of F- is also equal to C??. The concentration of remaining molecules of HF is equal to C(1 - ?). The equation for Kdiss calculation is as follows. Kdiss = (C???C??) / C(1 - ?) or Kdiss = C??2/(1 - ?) If the degree of dissociation is rather law, we can assume that "1 - ?"Weak electrolytes dissociate partially and reversibly: the equilibrium of the dissociation can be described by a standard equation (according to the law of mass action).That anion is OH- known as hydroxide ion.

uffer solution (buffer system) is a solution that keeps pH at approximately the same
level after the addition of small amount of strong acid or strong base.
Each buffer solution contains a conjugate pair (an acid and its conjugate base), which is
responsible for a solution ability to neutralize acids and bases added to it.
This definition explains that buffer system is something that can neutralize both acids and
bases. To understand this definition properly we must come back to the material on acids, bases and
pH in water solutions.
According to the Arrhenius theory, acids are electrolytes that produce only one type of
cation in water solution.
That cation is H+ more correctly represented as H3O+ known as hydronium ion.
Bases are electrolytes that produce only one type of anion in water solution.
That anion is OH– known as hydroxide ion. Water itself partially dissociates into both H+ and
OH– ions.
Electrolytes may be strong or weak.
Strong electrolytes dissociate completely and irreversibly.
Weak electrolytes dissociate partially and reversibly: the equilibrium of the dissociation can
be described by a standard equation (according to the law of mass action).
Kdiss = ([H+]∙[Anion–]) / [Acid] and Kdiss = ([OH–]∙[Cation–]) / [Base]
According to the law of dilution, the lower the concentration of an electrolyte, the higher the
degree of its dissociation. This statement can be approved mathematically. For example, for HF
dissociation at a given temperature Kdiss is constant, the concentration is equal to “C”, the degree of
dissociation is equal to “α”.
HF ↔ H+ + F–
If the fraction of HF molecules that really dissociated is equal to α, then the concentration of
H+ is equal to C∙α, and the concentration of F– is also equal to C∙α. The concentration of remaining
molecules of HF is equal to C(1 – α). The equation for Kdiss calculation is as follows.
Kdiss = (C∙α∙C∙α) / C(1 – α) or Kdiss = C∙α2/(1 – α)
If the degree of dissociation is rather law, we can assume that “1 – α” is almost the same as “1”.