Introduction to Chemical Reactions

Learning Reaction Types and Their Patterns

Synthesis

• A + B AB

• Element A + Element B Compound AB

• Magnesium Strip + Oxygen Gas Solid Magnesium Oxide

• 2 Mg(s) + O2 (g) 2 MgO (s) (white powder)

Decomposition

• AB A + B

• Compound AB Element A + Element B

• Aqueous hydrogen peroxide oxygen gas + liquid water

Splint Test

• A test used to determine the production of one of the following gases:

O2 – flame gets bigger and splint will relight

CO2 – flame will go out

H2 – popping noise (flame may go out from mini explosion!)

• 2 H2O2 (aq) O2 (g) + 2 H2O (l)

• ABCD AB + C + D

• Compound ABCD Compound AB + Element C + Element D

• Solid ammonium dichromate solid chromium

(III) oxide + nitrogen gas + water vapor

• ABCD AB + C + D

• Compound ABCD Compound AB + Element C + Element D

• Solid ammonium dichromate solid chromium

(III) oxide + nitrogen gas + water vapor

• (NH4)2Cr2O7 (s) N2 (g) + Cr2O3 (s) + 4 H2O (g)

Single Replacement - Cationic

• A + BC B + AC

• Element A+ Compound BC Element B+ Compound AC

• Note: Elements A & B are metals

• Copper wire + aqueous silver nitrate solid silver + aqueous copper (I) nitrate

• Cu(s) + AgNO3 (aq) Ag(s) + CuNO3 (aq) (blue)

• Iron nail + copper (II) chloride solution solid copper + iron (II) chloride solution

• Fe(s) + CuCl2 (aq) FeCl2 (aq) + Cu (s) (red)

• Solid zinc + aqueous hydrochloric acid hydrogen gas + aqueous zinc chloride

• Zn(s) + 2HCl(aq) ZnCl2 (aq) + H2 (g) (“pop” splint test)

Single Replacement - Anionic

• A + BC C + BA

• Element A + Compound BC Element C + Compound BA

• Note: Elements A & C are nonmetals

• Chlorine gas + aluminum bromide solution bromine gas + aluminum chloride solution

• 3Cl2 (g) + 2AlBr3 (aq) 3Br2 (g) + 2AlCl3 (aq)

Double Replacement

• AB + CD AD + CB

• Compound AB + Compound CD Compound AD + Compound BC

• aqueous copper (II) nitrate + aqueous sodium hydroxide copper (II) hydroxide (ppt) + aqueous sodium nitrate.

• Cu (NO3)2 (aq) + 2 NaOH (aq) Cu (OH)2 (s) + 2 NaNO3 (aq)

• aqueous silver nitrate + potassium chromate aqueous potassium nitrate + solid silver chromate

• AgNO3 (aq) + K2CrO4 (aq) KNO3 (aq) + Ag2CrO4 (s)

• In order for a double replacement reaction to occur, one of the following must be produced:

Gas

Water

Precipitate (ppt.)

Precipitation Animation

• http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/crm3s2_3.swf

Combustion

• Hydrocarbon + oxygen carbon dioxide + water + heat

• Hydrocarbon is a compound containing carbon, hydrogen and sometimes oxygen (CxHyOz)

• aqueous methanol + oxygen gas carbon dioxide gas + liquid water

• 2 CH3OH(aq) + 3 O2 (g) 2 CO2 (g) +

4 H2O (l) + heat

• methane gas + oxygen gas carbon dioxide gas + water vapor

• CH4 (g) + 2O2 (g) CO2 (g) + 2H2O(g)