Preparation of Buffers

A buffer contains a conjugate acid-base pair in approximately equal amounts. These amounts are relatively large so that the components of the buffer are always in excess of any added limiting reactant. There are several ways to prepare buffers, one of which is shown in the animation. Here the buffer is acidic and one hydronium ion is shown. Whether a buffer is acidic or basic is determined by the pKa of the weak acid and, in some cases, the ratio of the conjugate acid-base pair. In the animation, if the pKa of the weak acid is 5.00, and each molecule or ion represents one mole, then the pH is 4.92 where the hydronium ion in the solution simply represents the acidic nature of the buffer.