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 CO ₃ ²⁻ and 0.1 M HCO ₃ ⁻ B)0.1 M CO ₃ ²⁻ and 0.9 M HCO ₃ ⁻ C)0.5 M CO ₃ ²⁻ and 0.5 M HCO ₃ ⁻ D)0.1 M CO ₃ ²⁻ and 0.1 M HCO ₃ ⁻ E)They all have the same buffer capacity.

Question

Quizplus · Accepted Answer

The buffer capacity of a solution depends on the concentrations of the components of the buffer and their respective pKa values. The buffer capacity is maximum when the concentrations of the conjugate acid-base pair are equal. Option C has equal concentrations of the conjugate acid-base pair, therefore it has the highest buffer capacity. Options A and B have a larger concentration of one component over the other, which will decrease their buffer capacity. Option D has the lowest concentration of both components, so it will have the lowest buffer capacity. Therefore, option C is the best choice as it has equal concentrations of both components.

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

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