A buffer is an aqueous solution containing a weak acid and its conjugate base (a

Question

A buffer is an aqueous solution containing a weak acid and its conjugate base (acidic buffer) or a weak base and its conjugate acid(basic buffer). A buffer’s pH changes very little when a small amount of strong acid or base is added to it. It is used to prevent any change in the pH of a solution, regardless of solute.

Buffer solutions are resistant to pH change because of the presence of an equilibrium between the acid (HA) and its conjugate base (A–). The balanced equation for this reaction is:

HA H+ + A

We are able to prepare a buffer by determining the exact amount of acid and conjugate base needed to make a buffer of a certain pH, using the Henderson-Hasselbach equation:

pH = pKa + log([A]/[HA])

where pH is - log [H+], pKa is the acid dissociation constant, and [A^-] and [HA] are concentrations of the conjugate base and starting acid.

For a basic buffer, the equation is

B + H2O BH+ + OH

pOH = pKb + log ([HB+]/[ B ])

pH + pOH = 14

[HB+] = molar concentration of the conjugate base (M)

[ B ] = molar concentration of a weak base (M)

Explanation / Answer

[81 Explain the preparation of Buffers at a specific pH using the Henderson-Hasselbalch Equation?

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