Introduction to Balancing Chemical Equations

Key Concepts

• Unbalanced vs. Balanced Equations
  • Unbalanced Equation: Different numbers of one or more types of atoms on either side of the equation.
  • Balanced Equation: Same number of each type of atom on both sides of the equation.

Example 1: Hydrogen and Chlorine Gas to Hydrochloric Acid

• Word Equation: Hydrogen gas + Chlorine gas → Hydrochloric Acid
• Chemical Equation: H₂ + Cl₂ → HCl

Analyzing the Chemical Equation

• On left: 2 hydrogen (H) atoms, 2 chlorine (Cl) atoms.
• On right: 1 hydrogen (H) atom, 1 chlorine (Cl) atom.
• Conclusion: Unbalanced equation.

Balancing the Equation

• Adjust molecule numbers to balance atom types:
  • 2 HCl molecules needed.
• Balanced Chemical Equation: H₂ + Cl₂ → 2 HCl

Example 2: Hydrogen and Oxygen Gas to Water

• Chemical Equation: H₂ + O₂ → H₂O

Analyzing the Chemical Equation

• On left: 2 hydrogen (H) atoms, 2 oxygen (O) atoms.
• On right: 2 hydrogen (H) atoms, 1 oxygen (O) atom.
• Conclusion: Unbalanced due to oxygen.

Balancing the Equation

• Add another molecule of water (H₂O):
  • Now 2 H₂O molecules.
• Adjust hydrogen by adding another H₂.
• Balanced Chemical Equation: 2 H₂ + O₂ → 2 H₂O

Common Mistakes in Balancing

• Changing subscripts within a molecule (e.g., H₂O → H₂O₂):
  • Alters the compound identity (water vs. hydrogen peroxide).
• Only adjust coefficients in front of molecules, not subscripts.

Balancing Using Charts

• Example: Balancing nitrogen and hydrogen
  • Chemical Equation: N₂ + H₂ → NH₃

Steps to Balance

1. Create a chart listing atoms on both sides.
2. Record initial atom counts.
3. Identify imbalances and adjust coefficients:
   • Balance nitrogen by adding a 2 in front of NH₃.
   • Balance hydrogen by adding a 3 in front of H₂.

• Final Balanced Equation: N₂ + 3 H₂ → 2 NH₃

Practice

• Engage with practice problems for mastery.
• Watch video resources for additional examples and exercises.