acid-base equilibria #1

Weak Acid-Base Equilibrium

• Mixing a weak acid (NH₄⁺) and a weak base (HClO⁻) establishes equilibrium.

• NH₄⁺ acts as an acid and HClO⁻ acts as a base.

Equilibrium Reaction

• Proton transfer:

  • NH₄⁺ → NH₃ (loses a proton)

  • HClO⁻ → HClOH (gains a proton)

• Reverse reaction analysis:

  • HClOH (acid) loses a proton to form HClO⁻

  • NH₃ (base) gains a proton to form NH₄⁺

Strength of Acids and Bases

• Identify stronger acid: HClOH > NH₄⁺

  • HClOH: Stronger Acid (SR)

  • NH₄⁺: Weaker Acid (WR)

• Identify stronger base: NH₃ > HClO⁻

  • NH₃: Stronger Base (SR)

  • HClO⁻: Weaker Base (WR)

Equilibrium Position

• Stronger acid and base on product side; weaker acid and base on reactant side.

• Equilibrium favors the side with higher concentrations: Reactants are favored.

• General rule: Equilibrium favors the side with weaker acid and weaker base.

Equilibrium Constant

• K_q description: Concentration of products / Concentration of reactants.

• When products are favored: K_q > 1

• When reactants are favored: K_q < 1

• For this reaction: K_q < 1, because reactants are favored.