Balancing Chemical Equations Lecture Notes

Introduction

• Balancing chemical equations is essential in chemistry.
• Often perceived as difficult, but can be simplified with a systematic approach.
• Goal: Make the number of each type of atom the same on both sides of the equation.
• Total charge must be balanced as well.

Key Concepts

• Coefficients are used to balance equations.
• Equations have to be balanced both atomically and electrically.

Example: Combustion of Hexane

• Equation: C6H14 + O2 → CO2 + H2O
• Step 1: Assign a coefficient of zero to each molecule initially.

Balancing Process

1. Create a Table

   • Columns for reactants, products, and types of atoms (Carbon, Hydrogen, Oxygen).
   • Keep a running count of atoms as you balance.

2. Balancing Strategy

   • Begin with an element that appears only once on each side.
   • In this example, start with Carbon (not Oxygen).

3. Balancing Carbon

   • Identify which side has more Carbon atoms.
   • Assign a coefficient of 1 to hexane (C6H14) because it has the most Carbon.
   • Balance Carbon on the product side: Assign a coefficient of 6 to CO2.

4. Balancing Hydrogen

   • Find the number of Hydrogens: 14 on reactant side, 2 on product side.
   • Assign a coefficient of 7 to H2O to balance Hydrogen.
   • Update the Oxygen count in the table.

5. Balancing Oxygen

   • Calculate the total Oxygens needed on the product side.
   • Adjust the coefficient for O2 using a fraction if necessary.
   • Multiply throughout by the denominator of the fraction to get whole numbers.

Concluding the Process

• Final balanced equation: Multiply all coefficients by 2.
• Checked to ensure the lowest whole number ratios.
• Process confirmed to work regardless of starting element.

Tips

• Start with elements that appear only once per side.
• Use fractions to balance when necessary, then convert to whole numbers.
• Double-check balance using the table method.

Conclusion

• Balancing equations requires practice and a systematic approach.
• Ensure both atomic and electrical balance.
• Always check for lowest whole number ratios for the final balanced equation.