Strong vs Weak Acids and Bases

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Strong vs Weak Acids and BasesKa (acid
dissociation constant)
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Strong vs. Weak Acids

• Acids and bases are classified as strong or weak,
  based on how much they ionize in water
• Ionize when a molecule breaks into its ions
• Strong acids and strong bases are those that
  completely ionize in water

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The Strong Acids

• Hydrochloric Acid HCl
• Nitric Acid HNO3
• Sulfuric Acid H2SO4
• These are the only acids that will completely
  dissociate

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Strong Acid
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The Strong Bases

• Potassium hydroxide KOH
• Sodium hydroxide NaOH
• Calcium hydroxide Ca(OH)2
• Magnesium hydroxide Mg(OH)2

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Weak Acids/Weak Bases

• Weak acids only partially ionize in aqueous
  solution
• Generally a weak base, is anything without a
  hydroxide in its formula will only partially
  ionize

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Weak Acid
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Very Weak Acid
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Ka Acid Dissociation Constant

• Ka is used only for weak acids and is an
  indicator of how much the acid ionizes
  (dissociates)
• The closer the Ka is to 1, the stronger the acid
  and the more it ionizes
• The closer the Ka is to 0, the weaker the acid
  and the less it ionizes
• Similar to Ksp

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Weak Acids

• General Equation of a weak acid
• HA (aq) H2O (l) -gt H3O (aq) A- (aq)
• Weak acid
• Ka H A- numerator
• -------------------
• HA denominator
• Ka is the ratio of concentration of the
  dissociated form to the concentration of the
  undissociated

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Diprotic/Triprotic Acids

• Diprotic triprotic acids only lose one hydrogen
  at a time
• Phosphoric acid has 3 Ka values for each hydrogen