A buffer is a solution that resists changes in pH when a small amount of acid or base is added to it. It consists of a weak acid and its conjugate base or a weak base and its conjugate acid.
When NaOH is added to a buffer, it will react with the weak acid in the buffer to form the conjugate base of the weak acid. This will cause the pH of the buffer to increase, as the concentration of hydrogen ions (H+) in the solution decreases.
For example, consider a buffer solution consisting of acetic acid (CH3COOH) and its conjugate base, acetate ions (CH3COO-). When NaOH is added to this buffer, it will react with the acetic acid to form water and acetate ions:
CH3COOH(aq) + NaOH(aq) -> CH3COO- (aq) + H2O(l)
This reaction will cause the concentration of acetate ions in the solution to increase, which will in turn cause the pH of the buffer to increase.
The buffer capacity of the buffer will determine how much NaOH can be added before the pH changes significantly. Buffer capacity refers to the ability of a buffer to resist changes in pH when a certain amount of acid or base is added.
