Ionic Equilibria and Volumetric Analysis

Comprehensive vocabulary flashcards covering ionic equilibria, pH calculations, buffer systems, solubility constants, and volumetric analysis terminology based on the lecture transcript.

Ionic product of water ($K_w$)

The product of hydrogen and hydroxide ion concentrations, defined as $K_w = [H^+][OH^-]$, which equals $1.00 \times 10^{-14} \, \text{mol}^2 \, \text{dm}^{-6}$ at $25 \, ^\circ\text{C}$.

pH

A measure of the acidity or alkalinity of a substance, defined by the formula $\text{pH} = -\log[H^+]$.

Strong acid

An acid that ionises completely in the presence of water, such that $[H_3O^+] = [\text{HA}]$ for monoprotic acids.

Weak acid

An acid that ionises only partially in the presence of water, establishing an equilibrium represented by $\text{HA} + H_2O \rightleftharpoons H_3O^+ + A^-$.

Acid dissociation constant ($K_a$)

An equilibrium constant used to measure the strength of a weak acid, defined as $K_a = \frac{[H^+][A^-]}{[\text{HA}]}$.

$$pK_a$$

A logarithmic scale used to measure acid strength, defined as $\text{p}K_a = -\log(K_a)$, where a lower value indicates a stronger acid.

Titration curves

Also known as pH curves, these show the changes in pH that occur during an acid-base titration.

Equivalence point ($V_{eq}$)

The theoretical point in a titration where stoichiometrically equivalent amounts of analyte and titrant have reacted.

End point ($V_{ep}$)

The point in a titration where an observable physical change, such as a color change of an indicator, signaling the completion of the reaction.

Acid-base indicator

A substance (usually a weak acid) that changes colour as the pH of the solution in which it is dissolved changes.

$$pK_{In}$$

The log constant of an indicator at which point the indicator is halfway through its colour change and $\text{pH} = \text{p}K_{In}$.

Buffer solution

A solution whose pH does not change significantly when small amounts of acid or base are added to it.

Acidic buffer solution

A solution made by mixing a weak acid and its conjugate base that maintains an acidic pH.

Alkaline buffer solution

A solution made by mixing a weak base and its conjugate acid that maintains an alkaline pH.

Solubility product ($K_{sp}$)

The product of the concentrations of each ion in a saturated solution of a sparingly soluble salt at $298 \, \text{K}$, raised to the power of their relative concentrations.

Common ion effect

The reduction in the solubility of a dissolved salt by adding a solution of a compound that shares a common ion with the salt.

Titrant

A standard solution of known concentration that is added from a burette during a titration.

Analyte

The solution of unknown concentration which is being determined during a titration.

Primary standard

A pure compound used to prepare a standard solution of accurately known concentration directly, without needing standardization.

Standardization

The process of determining the actual concentration of a secondary standard solution by titrating it against a suitable primary standard.

Complexometric titration

A titration where the titrant is a chelating agent (like EDTA) that forms a water-soluble complex with the analyte metal ion.

Redox titration

A titration involving a reaction between an oxidizing agent and a reducing agent through the transfer of electrons.