Definitions of Acids and Bases

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Definitions of Acids and Bases

• Chemistry
• Mrs. Coyle

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Common Acids
Vinegar (acetic or ethanoic acid)
Citric Acid
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Characteristics of Acids

• Sour taste (for edible acids)
• May burn your skin
• Turn litmus paper from blue to red.

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Examples of Acids

• HCl Hydrochloric Acid
• H2SO4 Sulfuric Acid
• HNO3 Nitric Acid
• CH3COOH Acetic Acid (Vinegar)

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Common Bases
Ammonia
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Characteristics of Bases

• Bitter taste (for edible bases only)
• Can be poisonous and corrosive.
• Turn litmus from red to blue.

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Examples of Bases

• Sodium Hydroxide NaOH
• Potassium Hydroxide KOH
• Magnesium Hydroxide Mg(OH)2
• Ammonia NH3

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Three Definitions of Acids and Bases

• Svante Arrhenius (Swedish 1887)
• Bronsted- Lowry (Danish and English 1923
  independently proposed definition)
• Gilbert Lewis (American 1920s)

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Arrhenius Definition of Acids and Bases

• Acids produce hydrogen ions (H) in an aqueous
  solution, while bases produce hydroxide ion
  (OH-).
• Acid HCl (aq)? H (aq) Cl- (aq)
• Base NaOH(aq)? Na(aq) OH-(aq)

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Acids can have more than one ionizable hydrogen.
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Bronsted- Lowry Definition of Acids and Bases

• An acid is a proton (H) donor.
• A base is a proton (H) acceptor.
• Example
• HF H2O?? H3O F-
• Acid Base
• H3O hydronium ion

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Conjugate Acids and Bases

• General expression
• HA (aq) H2O (l)? H3O (aq) A- (aq)
• Acid Base Conjugate Conjugate
• Acid Base

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Conjugate Acids and Bases

• Conjugate acid is the particle formed that has
  received the proton. (ex H3O)
• Conjugate base is the particle left from the acid
  once it has donated the proton.

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Ammonia

• NH3(aq) H2O (l) ?? NH4 (aq) OH- (aq)
• Base Acid Conjugate Conjugate
• Acid
  Base

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Note

• Water acts as an acid and as a base. It is
  amphoteric.

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Lewis Acids and Bases

• An acid accepts a pair of electrons.
• A base donates a pair of electrons.
• This is a more general definition than the
  previous two.

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Example of a Lewis Acid and Base
NH3 H ? NH4
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Three Models of Acids and Bases