Solutions that resist changes in pH upon addition of small amounts of acid or base are called?

Solutions that resist changes in pH upon addition of small amounts of acid or base are called?

• A. Saturated solution
• B. Buffer solution
• C. Neutral solution
• D. Dilute solution

Answer: (B)

A buffer resists changes in pH because it contains a weak acid and its conjugate base (or a weak base and its conjugate acid) that work together to neutralize added acid or base. When small amounts of acid are added, the conjugate base part reacts with the extra H+ to form more of the weak acid, limiting the drop in pH. When small amounts of base are added, the weak acid donates H+ to neutralize OH−, forming more of the conjugate base and keeping the pH from rising much. This balancing act keeps the hydrogen ion concentration relatively stable. Common examples include a solution of acetic acid with its salt, sodium acetate, or the carbonic acid/bicarbonate system in blood. In contrast, saturated solutions aren’t inherently resistant to pH changes because their defining feature is the limit of solubility, not pH buffering. A neutral solution is around pH 7 but will still shift pH with added acid or base if it lacks buffering components. A dilute solution has fewer solute particles and likewise does not inherently resist pH changes.

A buffer resists changes in pH because it contains a weak acid and its conjugate base (or a weak base and its conjugate acid) that work together to neutralize added acid or base. When small amounts of acid are added, the conjugate base part reacts with the extra H+ to form more of the weak acid, limiting the drop in pH. When small amounts of base are added, the weak acid donates H+ to neutralize OH−, forming more of the conjugate base and keeping the pH from rising much. This balancing act keeps the hydrogen ion concentration relatively stable.

Common examples include a solution of acetic acid with its salt, sodium acetate, or the carbonic acid/bicarbonate system in blood. In contrast, saturated solutions aren’t inherently resistant to pH changes because their defining feature is the limit of solubility, not pH buffering. A neutral solution is around pH 7 but will still shift pH with added acid or base if it lacks buffering components. A dilute solution has fewer solute particles and likewise does not inherently resist pH changes.