Question

Which mixture could be a useful buffer in a solution?

Answer 1

A useful buffer in a solution is composed of a weak acid and its conjugate base or a weak base and its conjugate acid, such as acetic acid and sodium acetate or ammonia and ammonium chloride with about equal concentrations of both components.

Step-by-step explanation:

A mixture that could be useful as a buffer in a solution would be one that contains a weak acid and its conjugate base, or a weak base and its conjugate acid. A good example of a buffer mixture is a solution of acetic acid (HC₂H₃O₂, a weak acid) and sodium acetate (NaC₂H₃O₂, a salt derived from that weak acid). Another illustrative example is a mixture of ammonia (NH₃, a weak base) and ammonium chloride (NH₄Cl, a salt derived from that weak base). To be effective, a buffer solution should have about equal concentrations of its acid and base components. The buffer capacity is higher when both components are in higher molarity. For instance, a 1.0 M solution of acetic acid and sodium acetate will have a more substantial buffer capacity compared to a 0.10 M solution of the same composition, even if both solutions initially have the same pH. Buffers work by stabilizing the pH level of a solution, resisting dramatic changes when small amounts of strong acids or bases are added. They do this by allowing the weak acid to react with any added base and the weak base to react with any added acid, which keeps the solution's pH relatively unchanged.

Answer 2

Mixtures of a weak acid and its conjugate base, such as HOAc and the OAc- ion, are called buffers. The term buffer usually means "to lessen or absorb shock." These solutions are buffers because they lessen or absorb the drastic change in pH that occurs when small amounts of acids or bases are added to water. Adding a single drop of 2 M hydrochloric acid to 100 mL of pure water changes the pH from 7 to 3.