Synthesis, Decomposition, Combustion

Two species combine to create one Often, you will see two elements reacting to

make a compound

Ex: 2Na + Cl2 2 NaCl

Synthesis

1. Metal Oxides and Water◦ Produces a metal hydroxide compound (basic)◦ Ex: Na2O + H2O 2 NaOH

2. Non-metal Oxides and Water◦ Produces a solution that is acidic◦ Acid Precipitation◦ Ex: SO2 + H2O H2SO3

Specialized type of Synthesis

Acid Precipitation

Acid Precipitation Effects

One species breaks down into at least two different species

Often, this will be a compound breaking down into elements

Ex: 2 H2O 2H2 + O2

Decomposition

1. Bicarbonates (hydrogen carbonates)◦ Carbon dioxide gas is formed◦ Other products: carbonate and water vapour◦ Ex: 2 KHCO3 K2CO3 + H2O + CO2

2. Carbonates◦ Under extreme heating conditions◦ Produces an oxide and carbon dioxide gas◦ Ex: K2CO3 K2O + CO2

Specialized Types of Decomposition

4. Nitrates◦ When a metal nitrate decomposes, it forms a

metal nitrite and oxygen gas◦ Ex: 2 KNO3 2 KNO2 + O2

5. Hydroxides◦ When a metal hydoxide decomposes, it forms a

metal oxide and water◦ Ex: Mg(OH)2 MgO + H2O

There are more complex decompositions…

Video

An element or compound is reacting with oxygen, accompanied by a release of energy as heat or light

Products will always include an oxide Hydrocarbons: made of carbon and

hydrogen◦ Ex: propane (C3H8), gasoline, methane (CH4)…

Combustion

Complete Combustion: efficient combustion with ample amounts of oxygen◦ Flames are blue, indicating a higher temperature◦ Products: Carbon dioxide and water◦ Ex: CH4 + 2 O2 CO2 + 2H2O

Incomplete combustion: combustion when there is not enough oxygen◦ Flames are orange, indicating a “cooler”

temperature◦ Products are varied: can include carbon (soot)

and carbon monoxide (which are both pollutants), plus carbon dioxide and water

◦ Ex: 2 C3H8 + 7O2 2C + 2CO + 2CO2 + 8 H2O

When other chemicals undergo combustion, other oxides are created◦ Ex: NO2 and SO3 (non-metal oxides react with

water - dangerous for the environment)

Combustion of Hydrogen gas - http://www.youtube.com/watch?v=nLuOM9aOWvk

Combustion of other chemicals

P. 121 # 4, 5, 7 Worksheet

Homework