Lesson 1: Summary

Arrhenius Concept of Acids and Bases

• Definition: Acids increase H⁺ ion concentration in water; bases increase OH⁻ ion concentration.
• Strong Acids: Fully ionize (e.g., HCl, H_2​SO₄​).
• Strong Bases: Fully ionize (e.g., NaOH, KOH).
• Limitations: Only applies to aqueous solutions, excludes non-H⁺ or OH⁻ producing substances, does not address weak acids/bases.

Bronsted-Lowry Concept of Acids and Bases

• Definition: Acids are proton donors; bases are proton acceptors.
• Conjugate Pairs: Acid and base differing by one proton.
• Examples: NH₃+H₂O→NH₄⁺+OH⁻; water acts as an acid.

Strengths of Conjugate Acid-Base Pairs

• Relative Strengths: Stronger acids have weaker conjugate bases.
• Equilibrium: Favors formation of weaker acids and bases.
• Examples: HCl has a very weak conjugate base (Cl⁻), CH_3​COOH has a relatively stronger conjugate base (CH₃COO⁻).

Auto Ionization of Substances

• Water Ionization: 2H₂O⇌H₃O⁺+OH⁻; acts as both acid and base.
• Amphiprotic Species: Can donate or accept protons (e.g., bicarbonate ion HCO₃⁻​, water).

G. N. Lewis Electron-Pair Theory of Acids and Bases

• Lewis Base: Electron pair donor.
• Lewis Acid: Electron pair acceptor.
• Example: BF₃+NH₃→F₃B⁻NH₃​ is a Lewis acid, NH₃​ is a Lewis base.