Experiment 1: pH Measurements and Buffers

This set of vocabulary flashcards covers key terminology, chemical reagents, and mathematical formulas from the laboratory lecture on pH measurements and buffering capacity.

pH

The negative logarithm of the hydrogen ion concentration; a measure of the acidity or alkalinity of a solution.

Acid solution

A solution characterized by a high hydrogen ion concentration and a low pH.

Basic solution

A solution characterized by a low hydrogen ion concentration, a high hydroxide ion concentration, and a high pH.

Physiologic pH range

The pH range of most body fluids, typically between $6.5$ and $8.0$.

pH meter

An instrument composed of a glass electrode that generates an electrical potential depending on the hydrogen ion concentration, which is then converted to a pH reading.

Buffers

Solutions that resist drastic changes in pH when small amounts of acid or base are added, typically prepared by mixing weak acids and their salts.

Buffering range

The narrow pH range in which most buffers exhibit their action, defined as pH = pKa \text{ } \bgroup \neq \text{ } 1 \text{ } \boldsymbol{\rightleftarrows} \text{ } 1 \bgroup.

Maximum buffer capacity

The point at which an ideal buffer for a particular pH has a $pKa$ equal to that pH.

Henderson-Hasselbalch equation

$$pH = pKa + \text{log} \frac{[\text{proton acceptor}]}{[\text{proton donor}]}$$

Gumamela extract (GE)

An acid-base indicator prepared from the petals of a red gumamela flower by boiling them in water for $15 \text{ minutes}$.

Methyl Orange (MO)

A chemical indicator used in the experiment to detect pH changes, specifically used with phosphate and ammonium buffers.

Phenolphthalein (pph)

A chemical indicator used in the experiment to detect pH changes, specifically used with acetate buffer and $0.1 \text{ M NaOH}$.

Antacid

A health care product tested for its buffering action against stomach hyperacidity by reacting with $0.1 \text{ M HCl}$ and $0.1 \text{ M NaOH}$.

$$0.1 \text{ M NaOH}$$

Sodium hydroxide, a strong base used in the experiment to test the buffering capacity of distilled water and buffer solutions.

$$0.1 \text{ M HCl}$$

Hydrochloric acid, a strong acid used to test the buffering action and pH changes of various samples.

Limewater

A dilute solution of calcium hydroxide, denoted as $Ca(OH)_2$, used as one of the samples for pH determination.

Oral Rinse

A mouthwash solution tested for its effect on the pH of a donor's saliva immediately after gargling and at intervals of $15$, $30$, and $60 \text{ minutes}$.