Chemistry Chapter 16: Acid-Base Equilibria Flashcards

A set of vocabulary flashcards covering the key concepts, constants, and reaction types from the lecture on Acid-Base Equilibria.

Acid Ionization (or Acid Dissociation)

The process where an acid reacts with water to produce hydronium ion ($H_3O^+$) and the conjugate base ion.

Acid-Ionization Constant ($K_a$)

The equilibrium constant for the ionization of a weak acid, also called the acid-dissociation constant.

Degree of Ionization

The fraction of molecules that react with water to give ions in a weak electrolyte solution.

Percent Ionization

The degree of ionization expressed as a percentage.

Polyprotic Acid

An acid that supplies two or more protons ($H^+$ ions) during an acid–base reaction.

Diprotic Acid

An acid that can lose two protons in aqueous solution, such as sulfuric acid ($H_2SO_4$) or carbonic acid ($H_2CO_3$).

Triprotic Acid

An acid that supplies three protons per molecule during an acid–base reaction, such as phosphoric acid ($H_3PO_4$).

Common-Ion Effect

The shift in an ionic equilibrium caused by the addition of a solute that provides an ion that takes part in the equilibrium.

Acid Rain

Rain having a pH lower than that of natural rain (which has a pH of $5.6$), primarily caused by sulfur and nitrogen oxides.

Base-Ionization Constant ($K_b$)

The equilibrium constant for the ionization of a weak base in water.

Alkaloid

A naturally occurring base, such as quinine, whose basicity is due to a nitrogen atom that picks up protons from water.

Salt

An ionic compound containing a metal or polyatomic ion as the positive ion and a nonmetal or polyatomic ion (except oxide and hydroxide) as the negative ion.

Acid–Base Neutralization Reaction

The chemical reaction between an acid and a hydroxide base in which a salt and water are the products.

Salt Hydrolysis Reaction

The chemical reaction of a salt with water to produce hydronium ion, hydroxide ion, or both.

Spectator Ion

An ion that exists in the same form on both the reactant and product sides of a chemical reaction, such as $Cl^-$ in the hydrolysis of ammonium chloride.

Lewis Acid

A species that can form bonds by accepting an electron pair, such as the aluminum ion ($Al^{3+}$) forming bonds with the oxygen atoms in water.

Buffer

A solution characterized by the ability to resist changes in pH when limited amounts of acid or base are added to it.

Buffer Capacity

The amount of acid or base a buffer can react with before giving a significant pH change, dependent on the amount of acid and conjugate base present.

Henderson–Hasselbalch Equation

A mathematical formula used to calculate the pH of a buffer: $\text{pH} = \text{p}K_a + \log\frac{[A^-]}{[HA]}$.

Equivalence Point

The point in a titration where the quantity of titrant added is stoichiometrically equal to the quantity of the sample being titrated.

Indicator

A substance that changes color at a specific pH range to signal the endpoint of a titration, such as phenolphthalein or methyl red.

$K_w$ (Ion-Product Constant for Water)

The constant representing the product of the molar concentrations of hydronium and hydroxide ions, equal to $1.0 \times 10^{-14}$ at $25\,^\circ\text{C}$. Engineering notation: $K_w = K_a \times K_b$.