CHEM-242A Acid/Base Table Memorization

Methane (CH₄) pKa

50

Methane (CH₄) conjugate base

CH₃⁻ (Methide)

Ethylene (CH₂=CH₂) pKa

44

Ethylene (CH₂=CH₂) conjugate base

CH₂=CH⁻ (Vinyl anion)

Ammonia (NH₃) pKa

38

Ammonia (NH₃) conjugate base

NH₂⁻ (Amide)

Hydrogen (H₂) pKa

35

Hydrogen (H₂) conjugate base

H⁻ (Hydride)

Acetylene (HC≡CH) pKa

26

Acetylene (HC≡CH) conjugate base

HC≡C⁻ (Acetylide)

Water (H₂O) pKa

14 (15.7)

Water (H₂O) conjugate base

HO⁻ (Hydroxide)

Ammonium (NH₄⁺) pKa

9

Ammonium (NH₄⁺) conjugate base

NH₃ (Ammonia)

Acetic Acid (CH₃CO₂H) pKa

4.5

Acetic Acid (CH₃CO₂H) conjugate base

CH₃CO₂⁻ (Acetate)

Hydronium (H₃O⁺) pKa

0 (-2)

Hydronium (H₃O⁺) conjugate base

H₂O (Water)

Sulfuric Acid (H₂SO₄) pKa

-3

Sulfuric Acid (H₂SO₄) conjugate base

HSO₄⁻ (Hydrogen Sulfate)

Hydrobromic Acid (HBr) pKa

-7

Hydrobromic Acid (HBr) conjugate base

Br⁻ (Bromide)

Base strength trend

Increases moving up the table toward Methide

Acid strength trend

Increases moving down the table as pKa decreases toward HBr