Buffer Capacity Lab

Buffer Solutions A buffer solution is a solution that changes pH only slightly when small amounts of a strong acid or a strong base are added. A buffer contains significant concentrations of both a weak acid and its conjugate base, or a weak base and its conjugate acid.

Importance of Buffers Our blood is buffered to a pH of 7.4 Buffers are used when pH must be controlled in experiments. Proteins Enzymes

Sodium Acetate Buffer This buffer relies on the dissociation reaction of acetic acid. CH3COOH CH3COO- + H+

Pure water increases in pH by about 5 pH units when the OH– is added, and decreases by about 5 pH units when the H3O+ is added. In contrast, the same amounts of OH– and H3O+ added to a buffer solution barely change the pH.

Buffer Capacity and Buffer Range There is a limit to the ability of a buffer solution to neutralize added acid or base. This buffer capacity is reached before either buffer component has been consumed. As a rule, a buffer is most effective if the concentrations of the buffer acid and its conjugate base are equal or nearly so.