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.