Chemical Reactions in Aqueous Solutions

Reactions in Aqueous Solutions

Acid-Base Reactions

• Involve transfer of H+ ions (protons)
• Acid (H+ donor) + Base (H+ acceptor) → Salt + Water
• Examples:
  • HCl (acid) + NaOH (base) → NaCl (salt) + H2O (water)
  • CH3COOH (acid) + NaOH (base) → CH3COONa (salt) + H2O (water)

Hydration Reactions

• Involves the addition of water to a compound
• Examples:
  • CuSO4 (anhydrous) + 5H2O → CuSO4·5H2O (hydrated)
  • CaO (lime) + H2O → Ca(OH)2 (slaked lime)

Oxidation-Reduction (Redox) Reactions

• Involve transfer of electrons
• Oxidation: loss of electrons (increased oxidation state)
• Reduction: gain of electrons (decreased oxidation state)
• Examples:
  • Cu (metal) + AgNO3 (oxidizing agent) → Cu2+ (oxidized) + Ag (reduced)
  • Zn (metal) + CuSO4 (oxidizing agent) → Zn2+ (oxidized) + Cu (reduced)

Precipitation Reactions

• Involve formation of an insoluble solid (precipitate)
• Examples:
  • NaCl (aq) + AgNO3 (aq) → AgCl (precipitate) + NaNO3 (aq)
  • BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (precipitate) + NaCl (aq)

Complexation Reactions

• Involve formation of a coordination compound
• Examples:
  • Co(H2O)6³⁺ (aq) + 6NH3 (aq) → [Co(NH3)6]³⁺ (complex ion)
  • Cu²⁺ (aq) + 4NH3 (aq) → [Cu(NH3)4]²⁺ (complex ion)

Metathesis Reactions

• Involve exchange of partners between two compounds
• Examples:
  • NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (precipitate)
  • K2CO3 (aq) + Ca(NO3)2 (aq) → CaCO3 (precipitate) + 2KNO3 (aq)

Molecular Equations

• Represent the reactants and products in their molecular forms
• Examples:
  • 2H2 (g) + O2 (g) → 2H2O (l)
  • CaO (s) + H2O (l) → Ca(OH)2 (s)

Acid-Base Reactions

• Involve transfer of H+ ions (protons) between an acid and a base
• Acid (H+ donor) reacts with a base (H+ acceptor) to form a salt and water
• Examples of acid-base reactions include:
  • HCl (acid) + NaOH (base) → NaCl (salt) + H2O (water)
  • CH3COOH (acid) + NaOH (base) → CH3COONa (salt) + H2O (water)

Hydration Reactions

• Involve the addition of water to a compound
• Examples of hydration reactions include:
  • CuSO4 (anhydrous) + 5H2O → CuSO4·5H2O (hydrated)
  • CaO (lime) + H2O → Ca(OH)2 (slaked lime)

Oxidation-Reduction (Redox) Reactions

• Involve transfer of electrons between reactants
• Oxidation: loss of electrons, resulting in an increased oxidation state
• Reduction: gain of electrons, resulting in a decreased oxidation state
• Examples of redox reactions include:
  • Cu (metal) + AgNO3 (oxidizing agent) → Cu2+ (oxidized) + Ag (reduced)
  • Zn (metal) + CuSO4 (oxidizing agent) → Zn2+ (oxidized) + Cu (reduced)

Precipitation Reactions

• Involve formation of an insoluble solid (precipitate) from reactants
• Examples of precipitation reactions include:
  • NaCl (aq) + AgNO3 (aq) → AgCl (precipitate) + NaNO3 (aq)
  • BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (precipitate) + NaCl (aq)

Complexation Reactions

• Involve formation of a coordination compound from reactants
• Examples of complexation reactions include:
  • Co(H2O)6³⁺ (aq) + 6NH3 (aq) → [Co(NH3)6]³⁺ (complex ion)
  • Cu²⁺ (aq) + 4NH3 (aq) → [Cu(NH3)4]²⁺ (complex ion)

Metathesis Reactions

• Involve exchange of partners between two compounds
• Examples of metathesis reactions include:
  • NaCl (aq) + AgNO3 (aq) → NaNO3 (aq) + AgCl (precipitate)
  • K2CO3 (aq) + Ca(NO3)2 (aq) → CaCO3 (precipitate) + 2KNO3 (aq)

Molecular Equations

• Represent reactants and products in their molecular forms
• Examples of molecular equations include:
  • 2H2 (g) + O2 (g) → 2H2O (l)
  • CaO (s) + H2O (l) → Ca(OH)2 (s)