Question

The pH of a 25.0 mL sample of a buffer changed by one unit when 4.06 mL of 0.350 M NaOH was added to it. What is the base buffer capacity of this buffer?

Answer 1

The base buffer capacity is determined by calculating the amount of NaOH added and the volume of the buffer. It's the moles of base added per liter of buffer that resulted in a one-unit pH change. The base buffer capacity for this buffer is found to be 0.05684 mol/L.

Step-by-step explanation:

The question involves calculating the base buffer capacity of a buffer solution after the addition of NaOH has changed its pH. The base buffer capacity can be defined as the amount of strong base that can be added to a buffer solution before its pH changes significantly (usually by one pH unit). To calculate this, we need to know the number of moles of NaOH added to the buffer:

Moles of NaOH = Volume × Concentration = 0.00406 L × 0.350 mol/L = 0.001421 mol

The addition of 0.001421 mol of NaOH changed the pH of the buffer by one unit. The base buffer capacity is then the number of moles of base added per liter of buffer solution that caused this pH change. Given a 25.0 mL sample, we convert it to liters:

Base buffer capacity = Moles of NaOH / Volume of buffer in liters = 0.001421 mol / 0.025 L = 0.05684 mol/L