A buffer solution is one that
- A. has a pH of exactly 7
- B. neutralises all acids completely
- C. resists a change in pH when a small amount of acid or base is added
- D. conducts electricity better than water
Explanation
A buffer contains a reservoir of both a weak acid and its conjugate base, so added hydrogen ions are mopped up by the base and added hydroxide ions by the acid, and the pH barely moves. A buffer can be acidic or basic; a pH of 7 is not part of the definition. Blood is buffered near pH 7.4 mainly by the carbonic acid and hydrogen carbonate system.