Question

A solution of phosphate buffer at a pH of 7.0 with a pK2 = 6.82 would have more capacity to buffer the addition of

a) Hydrochloric acid
b) Sodium hydroxide
c) Acetic acid
d) Ammonia

Answer 1

A phosphate buffer at pH 7.0 with pK2 of 6.82 is most effective in buffering against the addition of hydrochloric acid due to its capacity to absorb H+ ions and resist changes in pH.

Step-by-step explanation:

A solution of phosphate buffer at a pH of 7.0 with a pK2 of 6.82 would have more capacity to buffer the addition of hydrochloric acid (HCl). Phosphate buffer systems consist of a mixture of a weak acid and its conjugate base and are able to resist changes in pH when small amounts of acid or base are added to it. Here, since pK2 is close to the pH of the buffer, it suggests ions are present in roughly equal concentrations, ideal for buffering. Adding hydrochloric acid would involve the weak base component of the buffer reacting to form the conjugate acid, effectively 'soaking up' the added H+ ions, thus minimizing the change in the pH of the solution.