3. Ionic Equilibria & Acid-Base Theories

Ionization

A chemical process where a neutral molecule reacts with water to form entirely new ions (e.g., (HCl + H_2O \rightarrow H_3O^+ + Cl^-)).

Dissociation

A physical process where a pre-existing ionic compound separates into its constituent ions in solution (e.g., (NaCl \rightarrow Na^+ + Cl^-)).

Arrhenius Acid/Base

An acid donates hydrogen ions ((H^{+})); a base donates hydroxide ions ((OH^{-})).

Brønsted-Lowry Acid/Base

An acid acts as a proton donor; a base acts as a proton acceptor.

Lewis Acid/Base

An acid acts as an electron pair acceptor; a base acts as an electron pair donor.

Weak Acid Drug Solubility

Soluble at high pH (basic environments) due to ionization; insoluble/precipitates at low pH.

Weak Base Drug Solubility

Soluble at low pH (acidic environments) due to ionization; insoluble/precipitates at high pH.

Acid Dissociation Constant (Ka)

Quantitative measure of the strength of an acid in solution; higher (K_{a}) (lower (pK_{a})) means a stronger acid.

Ampholytes

Molecules that can act as either an acid or a base, often existing as zwitterions with both positive and negative charges.

Autoprotolysis of Water

The self-ionization of water yielding (H_{3}O^{+}) and (OH^{-}), where (K_w = 1.0 \times 10^{-14}) at 25°C.