1. hydrocarbon + oxygen  carbon dioxide + water + energy
Types of Chemical Reactions:
Combustion Reactions
6.9
Combustion reactions occur when a substance reacts with oxygen. The products are usually an oxide and energy.
combustion
complete combustion
incomplete combustion
Complete Combustion of Hydrocarbons
When hydrocarbons undergo complete combustion, the general word equation is
 hydrocarbon + oxygen  carbon dioxide + water + energy
CxHy O2  CO H2O + energy
The complete combustion of butane (C4H10) would be
  C4H10(g) + O2(g)  CO2(g) + H2O(g) + energy
CAN YOU BALANCE THIS?

2. 6.9 Types of Chemical Reactions: Combustion Reactions
Incomplete Combustion of Hydrocarbons
When the oxygen supply is limited, hydrocarbons undergo incomplete combustion. This produces carbon (soot) and carbon monoxide gas, in addition to carbon dioxide and water.
The incomplete combustion of butane (C4H10) would be 
C4H10(g) + O2(g)  CO2(g) + H2O(g) + CO(g) + C(s) + energy
 CAN YOU BALANCE THIS REACTION?
Other Combustion Reactions
Other examples of combustion include 
4 Al(s) O2(g)  2 Al2O3(s) + energy
 2 H2(g) + O2(g)  2 H2O(g) + energy
combustion
complete combustion
incomplete combustion
Notice, other combustions have the equation
A + O  AO + energy
What type of reaction is this?

3. Corrosion
6.10
Corrosion is the breakdown of a metal as it reacts with chemicals in the environment.
Beneficial Corrosion
Sometimes corrosion of some metals forms a tough protective layer that prevents further corrosion. For example,
 4 Al(s) O2(g) 2 Al2O3(s) + energy
Copper also forms a protective coating when it corrodes?
DO YOU KNOW WHAT COLOUR THIS COATING IS?
corrosion
glavanized steel
electrolytes

4. RUSTING
The reddy-brown flaky material that is produced when metals containing iron corrode. It does not stick well, the way some other protective coatings do, so the metal wears away. This process continues until the metal is completely corroded or ‘eaten away’.
Rusting is caused or accelerated by
exposure to oxygen
exposure to water
exposure to electrolytes
Methods of preventing corrosion include
protective coatings (paint, plastic coatings, chrome)
corrosion-resistant materials (stainless steel, plastics)
galvanizing (galvanized steel) (a protective Zn coating)

5. QUESTIONS FOR REFLECTION
The corrosion of which metallic objects should cause the public great concern for their safety?
Why are our food cans made out of aluminum?
Can you think of a common household feature (outdoor) that is galvanized?
Why should a car owner care if her car paint gets scratched?
Should she care more or less if she lives in the Kalahari than if she lives in Mumbai?
Why is it important for a car to be clean and dry before being treating with a rust-proofing product?
How could your knowledge about corrosion impact your decision to get a tongue piercing or not?
Can you think of an important building made of metal? Why hasn’t it rusted away yet?