Question

You have 2 buffers A and B which have a pH of 7.4. Addition of 5 drops of 0.1N HCl changes the pH of buffer A to 6.8, whereas addition of 5 drops of 0.1 N HCl to buffer B changes its pH to 7.2.

Which is the better buffer and why?                                                                           

Answer 1

The aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa is called a Buffer. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. When a small or moderate amount of strong acid or base is added to it, its pH changes very little and thus it is used to prevent changes in the pH of a solution.

A buffer is able to resist pH change because the two components (conjugate acid and conjugate base) are both present in appreciable amounts at equilibrium and are able to neutralize small amounts of other acids and bases when the are added to the solution. Many life forms thrive only in a relatively small pH range so they utilize a buffer solution to maintain a constant pH.

Hence, Buffer B is the better buffer.