A popular buffer solution consists of carbonate (CO₃²¯) and hydrogen carbonate (HCO₃¯) conjugate acid-base pair. Which, if any, of the following such buffers has the highest buffer capacity? A) 0.9 M CO₃²¯ and 0.1 M HCO₃¯ B) 0.1 M CO₃²¯ and 0.9 M HCO₃¯ C) 0.5 M CO₃²¯ and 0.5 M HCO₃¯ D) 0.1 M CO₃²¯ and 0.1 M HCO₃¯ E) They all have the same buffer capacity.

Question

Quizplus · Accepted Answer

The highest buffer capacity occurs when the concentration of the weak acid (CO₃²¯) and its conjugate base (HCO₃¯) are equal. Therefore, the buffer with 0.5 M CO₃²¯ and 0.5 M HCO₃¯ has the highest buffer capacity. The other buffers have unequal concentrations of the conjugate acid-base pair, resulting in a lower buffer capacity.

A Popular Buffer Solution Consists of Carbonate (CO32¯) and Hydrogen

A Popular Buffer Solution Consists of Carbonate (CO₃²¯) and Hydrogen