Question

In a buffer solution made of acetic acid and sodium acetate, if a small amount of acid is added, the added acid will react with which of the following?

1) Acetic acid
2) Sodium acetate
3) Water
4) Hydrogen gas

Answer 1

When a small amount of acid is added to a buffer solution made of acetic acid and sodium acetate, the acid reacts with sodium acetate, forming more acetic acid and maintaining the pH balance due to the buffer's capacity.

Step-by-step explanation:

In a buffer solution made of acetic acid and sodium acetate, the addition of a small amount of acid will predominantly react with the sodium acetate. The added strong acid, which provides additional H+ ions, reacts with the acetate ion from the sodium acetate to form more acetic acid, according to the reaction:

H+(aq) + CH3CO2−(aq) → CH3CO2H(aq)

This reaction demonstrates how the buffer solution resists changes in pH upon the addition of strong acids or bases. Sodium acetate acts as a base by accepting the H+ ions, thus forming acetic acid and preventing a significant increase in hydronium ion concentration. Le Chatelier's principle explains that the equilibrium will shift left to consume the added products and maintain the pH level. A good buffer mixture should have about equal concentrations of acetic acid and sodium acetate to optimize its buffering capacity