What does a buffer do in pH terms?

What does a buffer do in pH terms?

• A. Increases pH dramatically
• B. Maintains constant salinity
• C. Reduces plant uptake
• D. Resists pH change

Answer: (D)

A buffer resists changes in pH by neutralizing added acids or bases. It typically contains a weak acid and its conjugate base (or a weak base and its conjugate acid). When acid is added, the conjugate base neutralizes some of the H+; when base is added, the weak acid donates H+ to counter it. This keeps the hydrogen ion concentration, and thus the pH, from shifting dramatically. The buffering effect is strongest near the buffer’s pKa and diminishes as you move away from that value. That’s why the correct description is that a buffer resists pH change. It doesn’t dramatically raise pH, it doesn’t fix salinity, and it doesn’t directly control plant uptake.

A buffer resists changes in pH by neutralizing added acids or bases. It typically contains a weak acid and its conjugate base (or a weak base and its conjugate acid). When acid is added, the conjugate base neutralizes some of the H+; when base is added, the weak acid donates H+ to counter it. This keeps the hydrogen ion concentration, and thus the pH, from shifting dramatically. The buffering effect is strongest near the buffer’s pKa and diminishes as you move away from that value.

That’s why the correct description is that a buffer resists pH change. It doesn’t dramatically raise pH, it doesn’t fix salinity, and it doesn’t directly control plant uptake.