Acid and Base Theory

Acid and Base theory contains 3 main concepts that is Arrhenius, Bronsted-Lowry & Lewis concept, these are listed below

Arrhenius Concept:

• • Acids: Substances that dissociate in water to produce hydrogen ions (H⁺).
  • Bases: Substances that dissociate in water to produce hydroxide ions (OH⁻).

• Example:

  • Acid: HCl(aq) → H⁺(aq) + Cl⁻(aq)
  • Base: NaOH(aq) → Na⁺(aq) + OH⁻(aq)
  • Neutralization: HCl(aq) + NaOH(aq) → H₂O(l) + NaCl(aq)

• Limitations:

  • Only applies to aqueous solutions.
  • Does not explain non-aqueous or gas-phase reactions.
  • Cannot account for substances without H⁺ or OH⁻

Bronsted-Lowry Concept:

• • Acids: Proton (H⁺) donors.
  • Bases: Proton (H⁺) acceptors.

• Example:

  • Acid: H₂O(l) + NH₃(aq) ⇌ OH⁻(aq) + NH₄⁺(aq)
  • Base: NH₃(aq) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)
  • Conjugate pairs: NH₄⁺/NH₃ and H₂O/OH⁻

• Advantages:

  • Applicable to both aqueous and non-aqueous solutions.
  • Explains acidic or basic behavior of substances without H⁺ or OH⁻

• Limitations:

  • Does not explain reactions without proton transfer.
  • Ignores electron-pair interactions.

Lewis Acid and Base Theory Concept:

• • Acids: Electron-pair acceptors.
  • Bases: Electron-pair donors.

• Example:

  • Lewis acid: BF₃ + F⁻ → BF₄⁻
  • Lewis base: F⁻ + BF₃ → BF₄⁻

• Advantages:

  • Applies to a wide range of reactions, including non-proton-transfer processes.
  • Covers reactions in all phases (gas, liquid, solid) and solvents.

• Limitations:

  • Can be too broad, classifying non-traditional acids/bases.
  • More abstract and less intuitive than other concepts.

Thank you for reading from Firsthope's notes, don't forget to check YouTube videos!