Which of the following solutions has the greater buffer capacity: 100 mL of 0.30 M HNO2-0.30 M NaNO2 or 100 mL of 0.10 M HNO2-0.10 M NaNO2? Explain.

Key Concepts

Buffer Capacity

Buffer capacity refers to the ability of a buffer solution to resist changes in pH upon the addition of small amounts of acid or base. It is determined by the concentrations of the weak acid and its conjugate base present in the solution. A higher concentration of these components results in a greater buffer capacity, allowing the solution to maintain a stable pH more effectively.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation is a mathematical formula used to calculate the pH of a buffer solution. It is expressed as pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base and [HA] is the concentration of the weak acid. This equation highlights the relationship between the concentrations of the acid and base in determining the pH and, consequently, the buffer capacity.

Concentration of Buffer Components

The concentration of buffer components, specifically the weak acid and its conjugate base, directly influences the buffer's effectiveness. In the given question, the first solution has a higher concentration (0.30 M) compared to the second solution (0.10 M). This increased concentration means that the first solution can neutralize more added acid or base, resulting in a greater buffer capacity.