Use for questions regarding solutions containing a mixture of a strong acid and weak base or vice versa.

A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its $\mathrm{pH}$ changes very little when a small amount of strong acid or base is added to it.

Example of such mixtures would be:

  • $\ce{H2CO3/KHCO3}$ (weak acid/strong base)
  • $\ce{NH3/NH4Cl}$ (weak base/strong acid)