The Buffering Ability of Commercial Products

Vocabulary and key concepts from the lecture notes on buffer solutions, titration, and pH stability in commercial products.

Aqueous buffer

A solution that has the ability to resist, for a time, changes in $pH$ that are caused by the addition of strong acids or strong bases.

Buffer Components

A weak acid and its conjugate base, or a weak base and its conjugate acid.

Buffer Concentration

The molar amount of the buffer species; higher concentrations make the buffer stronger and able to soak up more $H_3O^+$ or $OH^-$ ions.

Hydronium ion

The chemical species represented by the symbol $H_3O^+$ that reacts with a buffer's conjugate base.

Hydroxide ion

The chemical species represented by the symbol $OH^-$ that reacts with a buffer's weak acid.

Acetic acid and sodium acetate

An example of a buffer system where acetic acid ($CH_3COOH$) is the weak acid and sodium acetate ($CH_3COONa$) provides the conjugate base.

Carbonic acid and sodium bicarbonate

A buffer system made using the weak acid $H_2CO_3$ and the bicarbonate source $HCO_3^-$ to resist changes in $pH$.

Henderson-Hasselbalch Equation

The formula $pH = pK_a + \text{log}\frac{[A^-]}{[HA]}$ used to determine the $pH$ of a buffer solution.

$pK_a$ of Acetic Acid

The negative log of the acid dissociation constant ($1.8 \times 10^{-5}$), which equals $4.74$.

Equivalence Point

The point in a titration where the the moles of titrant and analyte are equal; for a weak acid and strong base titration, the $pH$ is above $7$ due to the conjugate base reacting with water.

Half-Equivalence Volume

The point in a titration where the volume of base added is half that of the equivalence volume, resulting in $[HA] = [A^-]$ and $pH = pK_a$.

Buffer Range

The effective $pH$ range of a buffer, typically covering the concentration ratios of the conjugate acid-base pair from $10:1$ to $1:10$, or $pK_a \times 1$.

Microbiological stability

One of the physical, chemical, and biological factors in food that is maintained by controlling $pH$ with buffers.