Glossary
Buffer
A solution that resists drastic changes in pH upon the addition of small amounts of acid or base. It typically consists of a weak acid and its conjugate base, or a weak base and its conjugate acid.
Example:
The bicarbonate system in human blood acts as a crucial buffer, preventing dangerous pH swings that could harm cells and enzymes.
Buffer Capacity
The amount of acid or base a buffer solution can neutralize before its pH changes significantly. It quantifies a buffer's effectiveness in resisting pH shifts.
Example:
A large volume of ocean water has a high buffer capacity, allowing it to absorb significant amounts of atmospheric CO2 without drastic pH changes.
Concentration (in buffer capacity)
The amount of solute present in a given volume of solution. For buffers, higher concentrations of both the weak acid and conjugate base directly lead to greater buffer capacity.
Example:
To create a more robust buffer for a titration experiment, increasing the concentration of both the weak acid and its conjugate base is essential.
Conjugate base
The species formed when a weak acid donates a proton (H+). It is capable of accepting a proton to reform the weak acid, thus neutralizing added acid.
Example:
In an acetic acid buffer, the acetate ion () serves as the conjugate base, readily reacting with any added H+ ions to maintain pH.
Henderson-Hasselbalch equation
An equation that relates the pH of a buffer solution to the pKa of the weak acid and the ratio of the concentrations of the conjugate base to the weak acid.
Example:
Using the Henderson-Hasselbalch equation, a biochemist can precisely calculate the pH of a buffer needed for a specific enzyme reaction.
Moles (in buffer capacity)
A unit of amount of substance, representing Avogadro's number of particles. The total number of moles of the weak acid and conjugate base in a buffer directly determines its capacity to resist pH changes.
Example:
If you double the moles of both the weak acid and its conjugate base in a buffer, you effectively double its ability to neutralize added acid or base.
Weak acid
An acid that only partially dissociates in water, meaning it does not donate all of its protons to the solution. It is a key component of a buffer system.
Example:
Citric acid, found in many fruits, is a common weak acid used in food preservation due to its buffering properties.
pH
A measure of the acidity or alkalinity of a solution, defined as the negative logarithm of the hydrogen ion concentration. Buffers are designed to resist significant changes in this value.
Example:
Maintaining a stable pH in swimming pools is crucial to prevent algae growth and ensure swimmer comfort.