Lecture on Hydrocarbons as Fuels

Introduction

• Lecture focuses on hydrocarbons and their use as fuels.
• By the end of the session, students should be able to:
  • Describe the use of hydrocarbons as fuels.
  • Write balanced equations for the complete combustion of hydrocarbons.

Properties of Hydrocarbons

• Short-chain hydrocarbons:
  • Highly flammable.
  • Low boiling points.
• Long-chain hydrocarbons:
  • Less flammable.
  • Higher boiling points.
  • Higher viscosity, meaning they flow slowly.

Hydrocarbons as Fuels

• Commonly used in ships, planes, and cars.
• Key Fact: Hydrocarbon fuels release energy when combusted.

Combustion Process

• Combustion involves hydrocarbons reacting with oxygen.
• Carbon and hydrogen are oxidized during combustion.
• Complete Combustion:
  • Occurs when oxygen is unlimited.
  • Produces carbon dioxide and water.

Writing Balanced Equations

Example: Methane Combustion

1. Initial Equation: Methane + O2 → CO2 + H2O
2. Balance Carbon Atoms:
   • 1 C in methane = 1 C in CO2 (Balanced)
3. Balance Hydrogen Atoms:
   • 4 H in methane, only 2 H in H2O (Not balanced)
   • Add a coefficient of 2 in front of H2O to balance hydrogen.
4. Balance Oxygen Atoms:
   • Total 4 O needed on the right.
   • Add a coefficient of 2 in front of O2 on the left.

Practice Problem

1. Balance Carbon Atoms:
   • 3 C on the left, 1 C in CO2 on the right.
   • Add a coefficient of 3 in front of CO2.
2. Balance Hydrogen Atoms:
   • 8 H on the left, 2 H in H2O (Not balanced).
   • Add a coefficient of 4 in front of H2O.
3. Balance Oxygen Atoms:
   • 6 O in CO2 and 4 O in H2O = 10 O total on the right.
   • Add a coefficient of 5 in front of O2 on the left.

Additional Resources

• Practice questions available in the vision workbook.