Acids and Bases - Lesson 30 Notes

Key Concepts of Acids and Bases

  • Differentiation

    • Strong Acids/Bases:

    • Ionize/dissociate completely in water.

    • Produce high concentrations of ions leading to better electrical conductivity.

    • Example: Hydrochloric acid (HCl), Sodium hydroxide (NaOH).

    • Weak Acids/Bases:

    • Partially ionize/dissociate in water (5% or less).

    • Lower concentrations of ions result in lesser conductivity.

    • Example: Acetic acid (CH3COOH), Ammonia (NH3).

  • Ionization and Conductivity

    • Strong acids and bases are better conductors of electricity due to high ion concentration.
    • Conductivity tester observations:
    • 1.0 mol/L HCl vs 0.1 mol/L HCl:
      • Higher concentration in the former leads to higher conductivity.
    • 1.0 mol/L NaOH vs 1.0 mol/L NH3:
      • NaOH, being a strong base, dissociates completely, creating more ions than NH3, a weak base.

  • Types of Acids and Bases

    • Monoprotic Acids & Bases:

    • Definition: Acids/Bases that release or react with one ionizable hydrogen (H+).

    • Example:

      • Acid: HCl (aq)
      • Base: NaOH (aq)

    • Polyprotic Acids & Bases:

    • Definition: Acids/Bases that can release or react with more than one hydrogen ion.

    • Example:

      • Acid: Sulfuric Acid (H2SO4)
      • Step 1: H2SO4 (aq) + H2O (l)
        ightarrow H3O^+ (aq) + HSO4^- (aq)
      • Step 2: HSO4^- (aq) + H2O (l)
        ightleftharpoons H3O^+ (aq) + SO4^{2-} (aq)
      • Base: Hydrazine (N2H4) (l)

  • Weak Acids/Bases in Biology

    • Buffers:

    • Combinations of weak acids and bases crucial in maintaining pH levels in biological systems.

    • Example: Blood chemistry regulation.

    • Environmental Impact:

    • Weak acids like sulfurous acid contribute to acid rain formation

  • Examples of Acids and Bases

    • Monoprotic Acid: Hydrochloric acid (HCl)
    • Monoprotic Base: Sodium hydroxide (NaOH)
    • Polyprotic Acid: Sulfuric acid (H2SO4)
    • Polyprotic Base: Hydrazine (N2H4)
    • Weak Acid: Acetic acid (CH3COOH)
    • Strong Acid: Hydrochloric acid (HCl)
    • Strong Base: Sodium hydroxide (NaOH)
    • Weak Base: Ammonia (NH3)
    • Metallic Oxide: Calcium oxide (CaO) forms a base in water.
    • Non-metallic Oxide: Sulfur dioxide (SO2) forms an acid in water.

  • Formic Acid Analysis

    • Formic acid (HCOOH) is classified as a weak acid due to partial ionization.

  • Hydronium Ion Concentration

    • Statement: A 0.10 mol/L solution of H2SO4 cannot be assumed to have double the hydronium ions compared to HCl, as H2SO4 partially dissociates to form HSO4- which is a weak acid.
    • Key Point: Both are strong acids, but sulfuric acid’s dissociation is not complete.