1. Types of Chemical Reactions: Combustion & Corrosion

2. Combustion when a fuel reacts quickly with oxygen
produces oxides and energy
important source of fuel is hydrocarbons

3. Complete Combustion of Hydrocarbons
if lots of oxygen is available, complete combustion
produces carbon dioxide and water
hydrocarbon + oxygen  carbon dioxide + water + energy
CxHy + O2  CO2 + H2O + energy
Example
Complete combustion of butane (C4H10):
 2 C4H10(g) O2(g)  8 CO2(g) H2O(g) + energy 

4. Incomplete Combustion of Hydrocarbons
if oxygen supply is limited
produces carbon monoxide gas, carbon (soot), plus carbon dioxide and water
orange flames are often present
Example
C4H10(g) + 5 O2(g)  2 CO2(g) H2O(g) + CO(g) + C(s) + energy

5. Other Types of Combustion
other substance react with oxygen
forms oxides
General word equation: element + oxygen  oxide + energy
General chemical equation: A O2  AO + energy
Example: Mg(s) + O2(g)  2MgO(s) + energy
video clip

6. Corrosion
breakdown of a metal, due to a reaction with chemicals in the environment
common example?

7. Rust corrosion of iron reaction with oxygen and water
electrolytes act as a catalyst
can prevent with paint or plastic coating

8. 4 Al(s) + 3 O2(g)  2 Al2O3(s) + energy
Beneficial Corrosion
Sometimes corrosion of some metals forms a tough protective layer that prevents further corrosion
For example, Aluminum:
 4 Al(s) O2(g)  2 Al2O3(s) + energy