Understanding Chemical Equations

Introduction to Chemical Equations

• Chemical reactions are represented with chemical equations.
• Components of a chemical equation:
  • Reactants: Substances that react together (left-hand side).
  • Products: Substances that are produced (right-hand side).
  • Arrow: Indicates the direction of the reaction, from reactants to products.

Types of Chemical Equations

• Word Equations: Describe the reaction in words.
  • Example: Methane burns in oxygen to form carbon dioxide and water.
• Symbol Equations: Use chemical symbols for each molecule.
  • Example: CH₄ + O₂ → CO₂ + H₂O.

Important Considerations

• Molecular Form: Some elements exist naturally as molecules with two atoms.
  • Examples: Oxygen (O₂), Chlorine (Cl₂), Nitrogen (N₂).

Balancing Chemical Equations

• Balancing ensures the same number of each type of atom on both sides of the equation.
• Example 1: Methane Combustion
  • Initial equation: CH₄ + O₂ → CO₂ + H₂O
  • Balancing Process:
    • Left: 1 Carbon, 4 Hydrogens, 2 Oxygens
    • Right: 1 Carbon, 2 Hydrogens, 3 Oxygens
    • Steps:
      • Increase O₂ to 2: CH₄ + 2O₂ → CO₂ + H₂O (now 4 Oxygens on left)
      • Increase H₂O to 2: CH₄ + 2O₂ → CO₂ + 2H₂O (now balanced)
• Rules for Balancing:
  • Cannot change subscripts (small numbers) as it changes the substance.
  • Adjust coefficients (big numbers) to balance the number of atoms.
  • Must use whole numbers for coefficients.

Additional Example: Sulphuric Acid and Sodium Hydroxide Reaction

• Equation: H₂SO₄ + NaOH → Na₂SO₄ + H₂O
• Balancing Process:
  • Left: 3 Hydrogens, 1 Sulphur, 5 Oxygens, 1 Sodium
  • Right: 2 Hydrogens, 1 Sulphur, 5 Oxygens, 2 Sodiums
  • Steps:
    • Adjust NaOH to 2: H₂SO₄ + 2NaOH → Na₂SO₄ + H₂O (sodium balanced)
    • Add another H₂O: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O (now balanced)

Conclusion

• Balancing chemical equations involves ensuring equal numbers of each type of atom on both sides.
• Trial and error is often necessary.
• Double-check to ensure the equation is balanced.