Presentation on theme: "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."— Presentation transcript:
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. CH 3 COOH CH 3 COO - + 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 H 3 O + is added. In contrast, the same amounts of OH – and H 3 O + 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.