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pH and pOH of Strong Acids and Bases

Understanding the pH and pOH of strong acids and bases is fundamental in aqueous chemistry.

Strong Acids​

  • Definition: Completely dissociate in water, releasing H⁺ ions.
  • Common examples: HCl, HBr, HI, HNO₃, H₂SO₄
  • pH Calculation:
    • For monoprotic acids:
      pH = –log₁₀[H⁺]
    • [H⁺] is the molarity of the acid solution.

Strong Bases​

  • Definition: Completely dissociate in water, releasing OH⁻ ions.
  • Common examples: NaOH, KOH, Ba(OH)₂
  • pOH Calculation:
    • pOH = –log₁₀[OH⁻]
    • [OH⁻] is the molarity of the base solution.

Relationship Between pH and pOH​

  • pH + pOH = 14 (at 25°C)
  • Allows conversion between hydrogen ion concentration and hydroxide ion concentration.

Key Points​

  • Strong acids/bases fully dissociate, so no equilibrium calculation is needed.
  • Helps quickly determine the pH or pOH for titrations and neutralization reactions.
  • Useful for understanding buffer preparation limits and reaction predictions.

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