Define buffer capacity and how buffer concentration affects it.

Define buffer capacity and how buffer concentration affects it.

• A. Buffer capacity is the rate at which the buffer neutralizes acid, independent of concentration.
• B. Buffer capacity is the same for all buffers regardless of their composition.
• C. Buffer capacity depends only on temperature and not on concentrations.
• D. Buffer capacity is the maximum amount of strong acid or base a buffer can neutralize before pH changes appreciably; it increases with higher concentrations of the buffer components.

Answer: (D)

Buffer capacity is the amount of strong acid or base a buffer can neutralize before the pH changes appreciably. It reflects how effectively the buffer can resist pH drift under added perturbations. This capacity scales with how much buffering material is present—the total concentration of the buffering components. More HA and A− molecules mean more reactants available to neutralize added H+ or OH−, so the buffer can absorb a larger amount of acid or base before the pH shifts significantly. The effect is strongest near the pH where pH ≈ pKa, because both forms exist in substantial amounts and can readily respond to additions; increasing the overall concentration there increases the amount that must be added to produce a given pH change. Lowering the buffer concentrations reduces this absorbing power, making the solution easier to shift in pH with added acid or base.

Buffer capacity is the amount of strong acid or base a buffer can neutralize before the pH changes appreciably. It reflects how effectively the buffer can resist pH drift under added perturbations. This capacity scales with how much buffering material is present—the total concentration of the buffering components. More HA and A− molecules mean more reactants available to neutralize added H+ or OH−, so the buffer can absorb a larger amount of acid or base before the pH shifts significantly. The effect is strongest near the pH where pH ≈ pKa, because both forms exist in substantial amounts and can readily respond to additions; increasing the overall concentration there increases the amount that must be added to produce a given pH change. Lowering the buffer concentrations reduces this absorbing power, making the solution easier to shift in pH with added acid or base.