8.4 Acid-Base Theories

Recall: Arrhenius’ TheoryAcids:Acids:

Arrhenius theoryArrhenius theory: Any substance that, when dissolved in water, increases the concentration of hydrogen ion (H+)

Bases:Bases:Arrhenius theoryArrhenius theory: Any substance that, when

dissolved in water, increases the concentration of hydroxide ion (OH-)

Lone Hydrogen ions do not exist by themselves in solution. H+ is always bound to a water molecule to form a hydronium ion

The Bronsted-Lowry ConceptAcids:Acids:

Arrhenius theoryArrhenius theory: Any substance that, when dissolved in water, increases the concentration of hydrogen ion (H+)

Bronsted-Lowry conceptBronsted-Lowry concept: A proton donor or source

Bases:Bases:Arrhenius theoryArrhenius theory: Any substance

that, when dissolved in water, increases the concentration of hydroxide ion (OH-)

Bronsted-Lowry conceptBronsted-Lowry concept: A proton acceptor or receiver

Brønsted-Lowry Theory of Acids & Bases

General Equation

Brønsted-Lowry Theory of Acids & Bases

Brønsted-Lowry Theory of Acids & Bases

Brønsted-Lowry Theory of Acids & BasesNotice that water is both an acid & a base = amphoteric

Reversible reaction

Conjugate Acid-Base Pairs

Conjugate Acid-Base Pairs

Acids & BasesAcids & BasesFor the following Identify the conjugate acid and the conjugate base.

The conjugate refers to the acid or base produced in an acid/base reaction. The acid reactant produces its conjugate base (CBCB).

a. Al(OH)3 + 3 HCl AlCl3 + 3 H2O

b. Ba(OH)2 + 2 HC2H3O2 Ba(C2H3O2)2 + 2 H2O

c. 2 KOH + H2SO4 K2SO4 + 2 H2O

d. NH3 + H2O NH4+ + OH-

CB CACB CA

CB CACB CA

CB CACB CA

CA CBCA CB

Homework

• “Conjugate Acid Base Pairs” Worksheet