Acid

  1. Brønsted-Lowry Theory

    • Definition: An acid is a proton (H+H^+) donor.

    • General Formula: HA→H++A−HA \rightarrow H^+ + A^-

    • Example: HCl→H++Cl−HCl \rightarrow H^+ + Cl^-

    • Reaction Arrows: A single forward arrow (→\rightarrow) denotes complete dissociation (strong acid), whereas an equilibrium arrow (⇌\rightleftharpoons) denotes reversible/partial dissociation (weak acid).

  2. Arrhenius Theory

    • Definition: An acid is a substance that ionizes or dissociates in water to give hydrogen ions (H+H^+) as the only positive ions.

    • Equation 1: HNO<em>3→ionizes in waterH++NO</em>3−HNO<em>3 \xrightarrow{\text{ionizes in water}} H^+ + NO</em>3^-

    • Equation 2: HNO<em>3+H</em>2O→H<em>3O++NO</em>3−HNO<em>3 + H</em>2O \rightarrow H<em>3O^+ + NO</em>3^- (Note: H3O+H_3O^+ is the Oxonium ion / Hydronium ion).

  3. Lewis Theory

    • Definition: An acid is an electron-pair acceptor.

    • Coordinate (Dative Covalent) Arrows: In Lewis acid-base reactions, a dative arrow points from the electron pair donor (Lewis base) to the electron pair acceptor (Lewis acid).

    • Examples of Lewis Acids:

      • H+H^+: Needs a pair of electrons.

      • AlCl3AlCl_3: Aluminum chloride needs a pair of electrons to achieve a stable octet configuration.

  4. Additional Lewis Acid Example: BF3BF_3

    • Chemical Formula: BF3BF_3 (Boron Trifluoride)

    • Lewis Dot-and-Cross Diagram: Shows shared covalent bonds between a central Boron atom (BB) and three Fluorine atoms (FF).

    • Key Concept: Boron has only 6 electrons in its outer valence shell, falling short