CHEM105 Week 4 Lecture Notes

Types of Chemical Reactions

Polyatomic Ions

  • Polyatomic Anions (4 examples):
    • Sulfate: SO₄²⁻
    • Nitrate: NO₃⁻
    • Phosphate: PO₄³⁻
    • Carbonate: CO₃²⁻
  • Polyatomic Cation (1 example):
    • Ammonium: NH₄⁺

Steps to Create and Balance a Word-Based Chemical Equation

  • Step 1: Identify Reactants and Products
    • Determine the substances that undergo a change (reactants) and the substances produced (products).
  • Step 2: Write the Unbalanced Equation
    • Write the chemical formulas for reactants and products without worrying about coefficients.
  • Step 3: Balance the Equation
    • Adjust coefficients to ensure the same number of each type of atom on both sides of the equation.
  • Step 4: Ensure Correct States of Matter
    • Indicate states of matter (solid, liquid, gas, aqueous) next to each chemical formula.
  • Step 5: Verify Conservation of Mass
    • Double-check to ensure mass is conserved (the same number of each atom appears on both sides).

Formulas for Specific Compounds

  • Iron (II) Sulfate: FeSO₄
  • Iron (III) Sulfate: Fe₂(SO₄)₃
  • Zinc Oxide: ZnO
  • Aluminium Phosphate: AlPO₄
  • Sodium Nitrate: NaNO₃
  • Magnesium Nitrate: Mg(NO₃)₂
  • Barium Hydride: BaH₂
  • Calcium Carbonate: CaCO₃

Chemical Reaction Equations

  • Sodium Phosphate and Magnesium Chloride Reaction:

    • Equation: Na₃PO₄ (aq) + MgCl₂ (aq) → Mg₃(PO₄)₂ (s) + NaCl (aq)
    • States: Aqueous (aq) for soluble, and Solid (s) for precipitate.

  • Decomposition of Dihydrogen Dioxide (Hydrogen Peroxide):

    • Equation: 2 H₂O₂ (l) → 2 H₂O (l) + O₂ (g)
    • States: Liquid (l) for water and gaseous (g) for oxygen.

  • Hydrochloric Acid and Zinc Reaction:

    • Equation: 2 HCl (aq) + Zn (s) → ZnCl₂ (aq) + H₂ (g)
    • Type of Reaction: Single Replacement (or Displacement).

  • Calcium Hydroxide and Nitric Acid Reaction:

    • Equation: Ca(OH)₂ (s) + 2 HNO₃ (aq) → Ca(NO₃)₂ (aq) + 2 H₂O (l)
    • Type of Reaction: Neutralization.

  • Aluminium and Iron (III) Oxide Reaction:

    • Equation: 2 Al (s) + Fe₂O₃ (s) → 2 Fe (l) + Al₂O₃ (s)
    • Type of Reaction: Single Replacement.

Conclusion

  • Understanding these chemical reactions and the correct formulas is crucial for mastering chemistry concepts effectively. Practicing balancing equations and recognizing reaction types will greatly aid in exam preparation.