A 500.0-mL buffer solution is 0.100 M in HNO₂ and 0.150 M in KNO₂. Determine if each addition would exceed the capacity of the buffer to neutralize it. a. 250 mg NaOH

Key Concepts

Buffer Solutions

Buffer solutions are mixtures that resist changes in pH when small amounts of acid or base are added. They typically consist of a weak acid and its conjugate base, or a weak base and its conjugate acid. In this case, HNO2 (a weak acid) and KNO2 (the salt of its conjugate base) form a buffer that can neutralize added acids or bases.

Buffer Capacity

Buffer capacity refers to the amount of acid or base that a buffer solution can neutralize before a significant change in pH occurs. It depends on the concentrations of the buffer components; higher concentrations lead to greater capacity. In this scenario, the buffer's capacity will determine if the addition of NaOH exceeds its ability to maintain pH.

Calculating Moles of Added Substance

To assess the impact of adding a substance like NaOH to a buffer, it's essential to calculate the number of moles being added. This is done using the formula: moles = mass (g) / molar mass (g/mol). For 250 mg of NaOH, converting to grams and then using its molar mass allows for determining how many moles are introduced to the buffer system.