Which option defines buffers?

Which option defines buffers?

• A. Substances that increase reaction rates
• B. Substances that minimize changes in pH by interacting with H or OH ions
• C. Substances that act as solvents
• D. Substances that neutralize all acids

Answer: (B)

Buffers resist changes in pH by neutralizing small amounts of added acids or bases. They usually consist of a weak acid and its conjugate base, or a weak base and its conjugate acid. When a little acid is added, the conjugate base part binds the extra H+, forming the weak acid and preventing a large drop in pH. When a little base is added, the weak acid donates a proton, forming water and the conjugate base, which limits the rise in pH. This stabilizing action keeps the pH fairly steady, especially near the pKa of the buffer pair. Common examples include bicarbonate/carbonic acid in blood, and acetic acid/acetate in vinegar, as well as various phosphate buffers used in biology and lab settings. Buffer effectiveness is greatest within about one pH unit of the pKa and depends on the total concentration of the buffer components—the higher the concentration, the greater the capacity to resist pH changes. In contrast, substances that speed up reactions are catalysts, solvents simply dissolve solutes, and a buffer does not neutralize all acids; it maintains pH within a range rather than eliminating acidity entirely.

Buffers resist changes in pH by neutralizing small amounts of added acids or bases. They usually consist of a weak acid and its conjugate base, or a weak base and its conjugate acid. When a little acid is added, the conjugate base part binds the extra H+, forming the weak acid and preventing a large drop in pH. When a little base is added, the weak acid donates a proton, forming water and the conjugate base, which limits the rise in pH. This stabilizing action keeps the pH fairly steady, especially near the pKa of the buffer pair.

Common examples include bicarbonate/carbonic acid in blood, and acetic acid/acetate in vinegar, as well as various phosphate buffers used in biology and lab settings. Buffer effectiveness is greatest within about one pH unit of the pKa and depends on the total concentration of the buffer components—the higher the concentration, the greater the capacity to resist pH changes.

In contrast, substances that speed up reactions are catalysts, solvents simply dissolve solutes, and a buffer does not neutralize all acids; it maintains pH within a range rather than eliminating acidity entirely.