Understanding Chemical Equation Balancing

Feb 12, 2025

Balancing Chemical Equations

Introduction

  • Focus on balancing chemical equations.
  • Goal: Make sure atoms are equal on both sides of the reaction.

Example 1: Combustion of Propane (C₃H₈)

Reaction: C₃H₈ + O₂ → CO₂ + H₂O

  1. Balance Carbon (C):

    • 3 C on left, need 3 CO₂ on right.
    • Add 3 in front of CO₂.
  2. Balance Hydrogen (H):

    • 8 H on left, need 4 H₂O on right (8/2 = 4).
  3. Balance Oxygen (O):

    • 6 O from 3 CO₂ + 4 O from 4 H₂O = 10 O on right.
    • Need 5 O₂ on left (10/2 = 5).

Final Balanced Equation:

  • C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O

Example 2: Combustion of Butane (C₄H₁₀)

Reaction: C₄H₁₀ + O₂ → CO₂ + H₂O

  1. Balance Carbon (C):

    • 4 C on left, need 4 CO₂ on right.
  2. Balance Hydrogen (H):

    • 10 H on left, need 5 H₂O on right (10/2 = 5).
  3. Balance Oxygen (O):

    • 4 CO₂ gives 8 O, 5 H₂O gives 5 O = 13 O on right.
    • Use fraction: 13/2 O₂, multiply everything by 2 for whole numbers.

Final Balanced Equation:

  • 2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O

Example 3: Aluminum and Hydrochloric Acid

Reaction: Al + HCl → AlCl₃ + H₂

  1. Balance Chlorine (Cl):
    • 3 Cl on right, put 3 in front of HCl, but this gives odd H.
    • Multiply everything by 2, use 6 HCl, need 2 AlCl₃ and 3 H₂.

Final Balanced Equation:

  • 2 Al + 6 HCl → 2 AlCl₃ + 3 H₂

Example 4: Gallium and Copper Bromide

Reaction: Ga + CuBr → GaBr₃ + Cu

  1. Balance Bromine (Br):

    • 2 Br on left, 3 on right; LCM is 6.
    • Put 3 in front of CuBr, 2 in front of GaBr₃.
  2. Balance Copper (Cu):

    • 3 Cu on left, add 3 in front of Cu.

Final Balanced Equation:

  • 2 Ga + 3 CuBr → 2 GaBr₃ + 3 Cu

Example 5: Iodine and Fluorine

Reaction: I₂ + F₂ → IF₇

  1. Balance Fluorine (F):

    • 2 F on left, 7 on right; LCM is 14.
    • Put 7 in front of IF₇ and 2 in front of F₂.
  2. Iodine (I) is already balanced.

Final Balanced Equation:

  • I₂ + 7 F₂ → 2 IF₇

Example 6: Sulfur Dioxide and Oxygen

Reaction: SO₂ + O₂ → SO₃

  1. Balance Oxygen (O):
    • 4 O on left, 3 on right; use fraction.
    • Multiply by 2 for final equation.

Final Balanced Equation:

  • 2 SO₂ + O₂ → 2 SO₃

Example 7: Sodium and Sulfur

Reaction: Na + S₈ → Na₂S

  1. Balance Sulfur (S):

    • 8 S on left, need 8 on right, put 8 in front of Na₂S.
  2. Balance Sodium (Na):

    • 16 Na needed (8 S); put 16 in front of Na.

Final Balanced Equation:

  • 16 Na + S₈ → 8 Na₂S

Example 8: Sodium Phosphate and Magnesium Chloride

Reaction: Na₃PO₄ + MgCl₂ → NaCl + Mg₃(PO₄)₂

  1. Balance Phosphate (PO₄):

    • 2 PO₄ on right, put 2 in front of Na₃PO₄.
  2. Balance Sodium (Na):

    • Put 6 in front of NaCl.
  3. Balance Magnesium (Mg):

    • Put 3 in front of MgCl₂.

Final Balanced Equation:

  • 2 Na₃PO₄ + 3 MgCl₂ → 6 NaCl + Mg₃(PO₄)₂

Example 9: Potassium Sulfate and Aluminum Chloride

Reaction: K₂SO₄ + AlCl₃ → KCl + Al₂(SO₄)₃

  1. Balance Sulfate (SO₄):

    • Put 3 in front of K₂SO₄.
  2. Balance Aluminum (Al):

    • Put 2 in front of AlCl₃.
  3. Balance Chlorine (Cl):

    • Put 6 in front of KCl.

Final Balanced Equation:

  • 3 K₂SO₄ + 2 AlCl₃ → 6 KCl + Al₂(SO₄)₃

Example 10: Ammonia and Oxygen

Reaction: NH₃ + O₂ → NO + H₂O

  1. Balance Hydrogen (H):

    • Use 3 in front of H₂O for 6 H.
  2. Balance Nitrogen (N):

    • Put 2 in front of NO.
  3. Balance Oxygen (O):

    • Use fraction, then multiply everything by 2.

Final Balanced Equation:

  • 4 NH₃ + 5 O₂ → 4 NO + 6 H₂O

Example 11: Combustion of Ethanol

Reaction: C₂H₅OH + O₂ → CO₂ + H₂O

  1. Balance Carbon (C):

    • Put 2 in front of CO₂.
  2. Balance Hydrogen (H):

    • Put 3 in front of H₂O.
  3. Balance Oxygen (O):

    • Calculate and put 3 in front of O₂.

Final Balanced Equation:

  • C₂H₅OH + 3 O₂ → 2 CO₂ + 3 H₂O

Conclusion

  • Balancing equations ensures conservation of mass.
  • Practice with different types of reactions to improve skills.