pKA and Desired pH w/ Buffer Solutions

[laurence14b2f]

Hi everyone! Why is it crucial to select a weak acid and its conjugate base with pKa values close to the desired pH when creating a buffer solution? Thanks!

[Chem_Mod]

Hi, its crucial to have a pKa value close to pH because the buffer capacity is highest when pH=pKa, specifically when the concentration of weak acid and conjugate base are equal because the buffer solution will then be effective at both taking in acid and base
Hope this helps!