Lecture Notes: Writing Net Ionic Equations

Introduction to Net Ionic Equations

• Net ionic equations are used to show only the species that participate in a chemical reaction.
• Focus on the reaction between aqueous lead (II) nitrate and aqueous potassium chloride.

Steps to Write Net Ionic Equations

1. Predict the Products

• Type of Reaction: Double replacement reaction
• Product Pairings:
  • Lead pairs with chloride
  • Potassium pairs with nitrate
• Charges:
  • Potassium (K): +1
  • Nitrate (NO₃): -1
  • Lead (Pb): +2
  • Chloride (Cl): -1

2. Determine Solubility

• Use solubility rules to determine phases:
  • Potassium Nitrate (KNO₃): Aqueous (soluble)
  • Lead (II) Chloride (PbCl₂): Solid (insoluble)

3. Balance the Chemical Equation

• Balanced Equation:
  • 2 KCl + Pb(NO₃)₂ → 2 KNO₃ + PbCl₂
• Identify it as a precipitation reaction due to solid formation.

4. Write the Total Ionic Equation

• Split aqueous compounds into ions:
  • Pb(NO₃)₂ → Pb²⁺ + 2 NO₃⁻
  • 2 KCl → 2 K⁺ + 2 Cl⁻
  • 2 KNO₃ → 2 K⁺ + 2 NO₃⁻
  • PbCl₂ remains as PbCl₂(s)

5. Identify and Remove Spectator Ions

• Spectator Ions: Ions that appear unchanged on both sides:
  • K⁺ and NO₃⁻ are spectator ions.

6. Write the Net Ionic Equation

• Net Ionic Equation:
  • Pb²⁺ + 2 Cl⁻ → PbCl₂(s)

Additional Example: Acid-Base Reaction

Reaction: Sulfuric Acid and Sodium Hydroxide

• Type: Double replacement, acid-base neutralization
• Product Pairings:
  • Hydrogen pairs with hydroxide (forms H₂O)
  • Sodium pairs with sulfate
• Sodium Sulfate Formula: Na₂SO₄

Balancing the Equation

• Balanced Equation:
  • H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O
• States:
  • Na₂SO₄ is aqueous (soluble)

Total Ionic Equation

• Separate aqueous compounds:
  • H₂SO₄ → 2 H⁺ + SO₄²⁻
  • 2 NaOH → 2 Na⁺ + 2 OH⁻
  • Na₂SO₄ → 2 Na⁺ + SO₄²⁻
  • H₂O remains as H₂O(l)

Spectator Ions

• Na⁺ and SO₄²⁻ are spectator ions.

Net Ionic Equation

• Reduced Equation:
  • H⁺ + OH⁻ → H₂O

Conclusion

• Understanding and practicing these steps can simplify the process of writing net ionic equations.
• These examples illustrate how to handle both precipitation and acid-base reactions effectively.

• Additional Resources: Chemistry, physics, calculus, algebra, high school and college tutorial videos available on the presenter's channel.