1. Matter & Bonding Lesson # 9
Combustion

2. Combustion
A combustion reaction occurs when a hydrocarbon (a compound made of hydrogen and carbon) reacts with oxygen to produce water vapour, carbon dioxide, and energy in the form of heat.
General Formula:
CxHy + O2 → H2O + CO2 + heat
Since it releases energy, it is an exothermic reaction.

3. Combustion (continued)
Visuals - large amounts of heat and/or light can be seen, and possibly an explosion.
Real-Life Example: the burning of fossil fuels, using a gas BBQ, how a car runs.
Example: CH4 + 2 O2 → CO2 + 2 H2O
Example: C3H8 + 5 O2 → 3 CO2 + 4 H2O

4. Combustion’s Environmental Impact
Combustion of hydrocarbons releases carbon dioxide gas into the atmosphere.
Carbon dioxide is a greenhouse gas, which means it plays a role in global warming. The excess carbon dioxide can prevent thermal energy (heat) from escaping into space, thus warming our planet.
Combustion can also help the environment. When an oil spill occurs on land or water, it must first be set on fire before any contaminated soil can be removed for treatment, or before sponges can absorb the contaminated water.

5. Incomplete Combustion
Incomplete combustion occurs when oxygen is limited – instead of getting carbon dioxide as a product, carbon monoxide is produced (poisonous gas) or solid carbon (black soot), along with water.
2 C3H8 (g) + 7 O2 (g) (limited) → 6 CO (g) + 8 H2O (g)
C3H8 (g) + 2 O2 (g) (very limited) → C3 (s) + 4 H2O (g)

6. Practice Dicarbon tetrahydride + oxygen →
Tetracarbon hexahydride + oxygen (limited) →
Pentacarbon octahydride + oxygen (very limited) →