Potentiometric Titration Fundamentals

Vocabulary based on the core definitions, equipment requirements, and specific conditions for different types of potentiometric titration.

Potentiometric Titration

Methods of determining the equivalence point ($T.E.$) based on the dependence of indicator electrode potential on the volume of added titrant.

Differential Titration Curves

Graphs plotted in coordinates of $\frac{\Delta E}{\Delta V}$ vs $V(T)$ or the second derivative $\frac{\Delta^{2}E}{\Delta V^{2}}$ vs $V(T)$ to identify the equivalence point.

Integral Titration Curves

Graphs plotted in coordinates of $E$ or $pH$ vs $V(T)$, representing a first derivative relationship.

Indicator Electrode

An electrode whose potential depends on the concentration of ions involved in or formed during the titration process.

Reference Electrode

An electrode with a constant potential, such as calomel or silver chloride ($Ag/AgCl$) electrodes, which are electrodes of the $II$ type reversible to the anion.

Acid-Base Indicator Electrodes

pH-sensitive electrodes (usually the glass electrode) where the potential depends on the concentration of oxonium ions in the solution.

Condition for Multi-stage Acid Titration

In aqueous media, successive dissociation constants must differ by at least four orders of magnitude ($\frac{K_{1}}{K_{2}} \geq 10^{4}$) for a distinct potential jump.

Differentiated Titration in Non-aqueous Media

A technique used for mixtures like $HCl$ and $CH_{3}COOH$ where adding solvents like acetone lowers ionization to allow separate determination of components.

Redox Indicator Electrodes

Electrodes made of inert materials (such as platinum $Pt$ or gold $Au$) that act as electron carriers between redox systems.

Redox Titration Jump Threshold

For reactions where $m = n = 1$ and an error of $\pm 0.1\%$, the potential jump is noticeable if the difference in formal potentials $\Delta E^{o} \geq 0.4\,V$.

Mixed Potential

An unstable potential acquired by an electrode when one form (Ox or Red) is missing, often where dissolved $O_{2}$ acts as the oxidant and $H_{2}O$ as the reductant.

Precipitation Titration Indicators

Electrodes reacting to changes in concentration of cations or anions forming low-soluble compounds, including metallic electrodes (Type $I$) and Ion-Selective Electrodes ($ISE$).

Precipitation Mixture Titration Condition

Differential titration of several ions is possible if the solubility products ($K_{s}^{o}$) of the formed precipitates differ by at least 3 orders of magnitude.

Complexometric Titration Indicators

Metallic electrodes reversible to the components, $ISE$, or inert electrodes (e.g., platinum) when a redox pair like $Fe^{3+}/Fe^{2+}$ is used.