Classifying Chemical Reactions

Decomposition Description: Compounds break down Form: AB  A + B Example: MgO  Mg + O

Decomposition Decomposition of hydrogen peroxide  Hydrogen peroxide eventually becomes water and oxygen gas. H 2 O 2  H 2 O + O 2

Addition Description: Compounds are formed Form: A + B  AB Example: Mg + O  MgO

Addition (aka Synthesis) Burning magnesium in oxygen will create magnesium oxide Mg + O 2  MgO

Combustion Description: Burning in oxygen forms water, often CO 2 Form: C x + H x + O 2  H 2 O + CO 2 Example: H 2 + O 2  H 2 O

Combustion of hydrogen Hydrogen balloon

Not a good idea to fill a flying vehicle with a combustible gas

Single Displacement (aka Single Replacement) Description: One element replaces another in a compound Form: A + BC  B + AC Example: Mg + BeO  Be + MgO

Single Displacement

Double Displacement (aka Double Replacement) Description: Two elements switch places in two compounds Form: AB + CD  CB + AD Example: MgO + BeS  MgS + BeO

Double displacement reaction

You may have to turn a word equation into a chemical equation before classifying it. ***Don’t forget about the diatomic elements: H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

Example: The octane (C 8 H 18 ) in gasoline burns in oxygen to produce carbon dioxide and water Equation: Type of reaction: C 8 H 18 + O 2  CO 2 + H 2 O Combustion

We Do: Oxygen gas is bubbled over aluminum to make aluminum oxide Equation: Type of reaction:

You Do: Iron metal and water are formed by the reaction of iron (III) oxide and hydrogen. Equation: Type of reaction: