Equations

Types of Reactions

Four major classes

SynthesisDecomposition Single Replacement Double Replacement

Synthesis

A marriage of two substances (reactants) to form one new substance (product)

A + B AB

The reactants can either be elements or compounds.

The product is always one compound.

Example: C + O2 CO2

Decomposition

Opposite of synthesis A divorce of one substance (reactant) to

form two or more simpler substances (products)

AB A + B

The reactant is always one compound. The products can either be elements or

compounds. Example: 2 HgO 2 Hg + O2

Single Replacement

One element takes the place of another in a compound

The element can replace the first part of a compound, or it can replace the last part of a compound.

A + BC B + AC (cationic)

Single Replacement, cont

D + BC C + BD (anionic)

Element + compound element + compound

7 elements are diatomic: N2, H2, Cl2, O2, Br2, F2, I2

Example: Zn + 2 HCl ZnCl2 + H2

Double Replacement

The positive and negative portions of two compounds switch places.

Compound + compound compound + compound

AB + CD AD + CB Example: HCl + KOH HOH

+ KCl

Combustion Reactions

Two types of Combustion Reactions:

1. Complete CombustionCxHy + O2 CO2 + H2O

Always involves a hydrocarbon fuel source and oxygen as reactants, and carbon dioxide and water as products.

Occurs when oxygen levels are high.

Combustion Reactions

2. Incomplete Combustion CxHy + O2 CO + H2O

Always involves a hydrocarbon fuel source and oxygen as reactants, and carbon monoxide and water as products.

Occurs when oxygen levels are insufficient to support combustion.

COMBUSTION: 1. complete CxHy + O2 CO2 + H2O2. incomplete CxHy + O2 CO + H2O

When the reaction description includes the terms combusts, burns, oxidizes, or reacts with air, add oxygen as a reactant.

Determine whether the reaction is complete or incomplete combustion; then write the products.

Balance the carbons. Balance the hydrogens. Balance the oxygens.

COMBUSTION: 1. complete CxHy + O2 CO2 + H2O2. incomplete CxHy + O2 CO + H2O

A propane (C3H8) grill is lit on the outside deck.

C3H8 + O2 + H2O

COMBUSTION: 1. complete CxHy + O2 CO2 + H2O2. incomplete CxHy + O2 CO + H2O

A propane (C3H8) grill is lit in a closed garage.

C3H8 + O2 + H2O

COMBUSTION: 1. complete CxHy + O2 CO2 + H2O2. incomplete CxHy + O2 CO + H2O

A butane lighter (C4H10) burns completely.

C4H10 + O2 + H2O