Buffer Capacity Practice Test

A student prepares two buffers using the same weak acid/conjugate base pair. Equal volumes of each buffer are placed in beakers.

• Buffer P is made with moderate concentrations of both $\mathrm{HA}$ and $\mathrm{A^-}$.
• Buffer Q is made with much higher concentrations of both $\mathrm{HA}$ and $\mathrm{A^-}$.

The student adds the same small amount of strong base to both beakers. Which claim best describes which buffer has greater capacity and the key reason?

A student prepares two buffers in separate beakers, each containing a weak acid and its conjugate base:

• Buffer M: moderate total amount of $\mathrm{HA}$ and $\mathrm{A^-}$ (moderately concentrated)
• Buffer N: much larger total amount of $\mathrm{HA}$ and $\mathrm{A^-}$ (more concentrated)

Both buffers are prepared so that the ratio $\mathrm{A^-}/\mathrm{HA}$ is the same in each beaker. The student adds the same small amount of strong acid to both. Which conclusion is most appropriate?