The effect is similar if strong base is added to the buffer solution. The benzoic acid will neutralize the added base. A useful way to plot the fraction of each form of a conjugate acid-base pair is with an alpha fraction. An fraction is the ratio of the equilibrium concentration of one specific form of a solute divided by the total concentration of all forms of that solute in an equilibrium mixture. It is therefore a number between 0 and 1.
Alpha plots are another graphical means of describing an equilibrium solution.
See Figure 4.18 to see the correlation between a log-concentration plot and a titration curve. Mix a weak acid and a salt of its conjugate base in solution. Mix a weak acid and enough strong base to neutralize some of the weak acid. Mix a weak base and enough strong acid to neutralize some of the weak base. The buffer capacity can be defined as the amount of strong acid or strong base that causes a pH change of 1 in 1.0 L of buffer solution.