Answer:
A buffer solution is a mixture of two pair salts to maintain a stable pH.
Explanation:
This mixture is made always with a complementary pair of salts (one acid an another basic).
Example:
Acetic Acid (CH3COOH) and Sodium Acetate (NaH3COO).
So when you add a little bit more acid to this mixture, the basic part of the buffer, in this case the Sodium Acetate, will neutralize it and the pH will remain the same.
On the other hand, if the mixture receives some basic substance, the acid part of the buffer, the acetic acid, will neutralize it, so again the pH will remain the same.
