Understanding Chemical Equations

Introduction

• Chemical equations show what's happening in a chemical reaction.
• Word Equation Example: Methane burns in oxygen and turns into carbon dioxide and water.
  • Reactants: Methane and oxygen (left side of equation).
  • Products: Carbon dioxide and water (right side of equation).
  • Arrow: Represents the reaction from reactants to products.

Symbol Equations

• Use chemical symbols instead of words for easier representation.
• Example: CH4 (methane) + O2 -> CO2 + H2O.
  • Oxygen is represented as O2 (diatomic molecule).
  • Similar for chlorine (Cl2) and nitrogen (N2).

Balancing Chemical Equations

• Goal: Same total number of each type of atom on both sides of the equation.
• Example Issue:
  • Left: 1 Carbon, 4 Hydrogens, 2 Oxygens.
  • Right: 1 Carbon, 2 Hydrogens, 3 Oxygens.

Steps for Balancing

1. Trial and Error process.
2. Rules:

• Do not change the small numbers (subscripts) as they represent the chemical identity.
  • Change the big numbers (coefficients) to balance the atoms.

3. Example Solution:

• Put '2' in front of O2 to increase oxygen atoms to 4 on the left.
  • Then, increase H2O to 2 to balance hydrogens.

Example: Sulfuric Acid and Sodium Hydroxide

• Equation: Sulfuric Acid + Sodium Hydroxide -> Sodium Sulfate + Water.
• Balancing:
  • Start with least common elements, sodium and sulfur.
  • Sodium needs balancing, put '2' in front of Sodium Hydroxide.
  • Fix oxygen and hydrogen by adding another water molecule.
• Verification: Ensure equal atoms on both sides.

Conclusion

• Always double-check balanced equations.
• Balancing requires patience and practice.

These notes summarize the process and rules for writing and balancing chemical equations as discussed in the lecture.