What is a buffer?

What is a buffer?

• A. A compound that accelerates sharp changes in pH
• B. A compound that prevents sharp, sudden changes in pH
• C. A substance that increases hydrogen ion concentration
• D. A base that neutralizes acids completely

Answer: (B)

A buffer is a solution that resists changes in pH when small amounts of acid or base are added. This happens because it contains a weak acid and its conjugate base (or a weak base and its conjugate acid) that react with added H+ or OH-. If acid is added, the conjugate base neutralizes some of the added hydrogen ions, forming the weak acid and limiting pH drop. If base is added, the weak acid donates hydrogen ions to neutralize some of the hydroxide ions, forming water and the conjugate base, which limits pH rise. So the pH stays relatively stable over a range of additions. Buffers don’t completely eliminate pH change, and they don’t rely on a strong base that neutralizes all acid. They function by balancing the acid–base pair to moderate shifts in hydrogen ion concentration.

A buffer is a solution that resists changes in pH when small amounts of acid or base are added. This happens because it contains a weak acid and its conjugate base (or a weak base and its conjugate acid) that react with added H+ or OH-. If acid is added, the conjugate base neutralizes some of the added hydrogen ions, forming the weak acid and limiting pH drop. If base is added, the weak acid donates hydrogen ions to neutralize some of the hydroxide ions, forming water and the conjugate base, which limits pH rise. So the pH stays relatively stable over a range of additions. Buffers don’t completely eliminate pH change, and they don’t rely on a strong base that neutralizes all acid. They function by balancing the acid–base pair to moderate shifts in hydrogen ion concentration.