Question

explain how a solution containing 0.50 m acetic acid (hc2h3o2) and 0.50 m sodium acetate (nac2h3o2) can resist changes in ph when small amounts of either hcl or naoh are added.the sodium acetate/acetic acid solution is an example of a buffer. it contains appreciable quantities of both a weak acid (acetic acid) and its conjugate base (acetate ion.) the buffer resists changes in ph by removing the acetate ions that dissociate from an added strong acid or the spectator ions that dissociate from an added strong base. added strong acid reacts with some of the conjugate base in the buffer, and the added strong base reacts with some of the conjugate acid in the buffer.

Answer 1

Buffer solutions like a mixture of acetic acid and sodium acetate resist changes in pH upon the addition of acid or base by converting added H+ or OH- into water and the respective conjugate base or acid, maintaining nearly constant pH.

Step-by-step explanation:

Buffers are solutions that maintain a relatively constant pH when small amounts of acid or base are added. A 0.50 M acetic acid and 0.50 M sodium acetate buffer solution is an excellent example. This buffer consists of acetic acid, a weak acid, and sodium acetate, its conjugate base. When a strong acid like HCl is added to the buffer, the acetate ions from the sodium acetate react with the added hydronium ions to form more acetic acid, thus minimizing the change in pH:

H3O+ (aq) + CH3COO- (aq) → CH3COOH (aq) + H2O (l)

Similarly, if a strong base such as NaOH is added, the OH- ions from the NaOH react with the acetic acid to form acetate ions and water:

HC2H3O2(aq) + OH- (aq) → H2O(l) + C2H3O2- (aq)

This reaction also resists a large change in pH. The capacity of a buffer to resist pH change depends on the concentrations of the acid and its conjugate base; ideally, these should be roughly equal. The greater the concentration, the more effective the buffer will be.