Types of Chemical Reactions

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Types of Chemical Reactions

• Mrs. Coyle
• Contemporary Chemistry

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Types of Chemical Reactions

• Composition
• Decomposition
• Single Replacement (Displacement)
• Double Replacement (Displacement)
• Combustion

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Composition(Combination, Synthesis)

• Two or more substances combine to form a single
  substance.
• General equation
• A B ? AB
• example
• 2Na Cl2 ? 2NaCl
• http//jchemed.chem.wisc.edu/jcesoft/cca/cca0/Movi
  es/NACL1.html

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Decomposition

• A compound is broken into two or more products.
• General equation
• AB ? A B
• Example
• 2H2O? 2H2 O2

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Combustion
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Combustion of Coal
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Combustion of Coal
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• Coal Combustion Faces Controversy
• A 2007 MIT report found that coal contributes
  more to global carbon dioxide emissions than any
  other energy source.
• Coal combustion also emits other pollutants, such
  as sulfur dioxide and nitrogen oxides.
• Coal power continues to account for half of our
  nations electricity production.
• Ref http//www.enviroblog.org/2007/03/coal-combus
  tion-faces-controve.htm

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Combustion Reactions

• An element or compound reacts with O2, often
  producing energy as heat or light.

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Some Elements contained in Coal

• Carbon C
• Nitrogen N
• Sulfur S

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Combustion of an Element

• Examples
• C O2 ? CO2
• N2 2O2 ? 2NO2
• S O2 ? SO2

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More examples of Combustion of an Element

• 2Mg O2 ? 2MgO
• 4Fe 3O2? 2Fe2O3

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Combustion of Hydrocarbons

• Hydrocarbons are compounds of
• carbon and hydrogen.
• Examples
• Methane CH4
• Ethane C2H6

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Combustion of Hydrocarbons

• Complete Combustion produces CO2 and H2O
• Incomplete Combustion produces CO and H2O

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Examples

• Complete Combustion of Methane
• CH4 2O2 ? CO2 2H2O
• Incomplete Combustion of Methane
• 2CH4 3O2 ? 2CO 4H2O

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Single Replacement Reactions

• Also known as
• Single Displacement Reactions

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General Pattern for Metals in Single Replacement
Reactions

• A BC? AC B
• A and B are metals
• C is a non-metal

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General Pattern for Non-Metals in Single
Replacement Reactions

• X YZ? YX Z
• X and Z are non-metals
• Y is a metal

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Activity Series

• For one element to replace another the lone
  element must be more active than the element in
  the substance.
• See the Activity Series chart.

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Example Using Zinc in Single Replacement
Reactions with Acids

• Zinc Reacts with Acids to produce Hydrogen
• Reaction with Sulfuric Acid produces
• Zinc Sulfate plus Hydrogen
• Zn H2 SO4 ? Zn SO4 H2

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Reaction with Hydrochloric AcidZn 2 HCl? ZnCl2
H2
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Thermite Reaction 2 Al Fe2O3? Al2O3 2 Fe

• Aluminum reacts with Iron(III)Oxide to Produce
  Aluminum Oxide and Iron

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Uses of the Thermite Reaction

• Used to weld steel

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Smelting

• A method of producing a metal from its ore using
  single replacement reactions.

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Smelting

• Carbon will displace the metal from its oxide to
  produce the metal plus carbon dioxide.
• CuO C ? Cu CO2

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Example

• 2NaBr Cl2 ? 2NaCl Br2

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Examples

• Na HCl ?
• Ca AlCl3 ?
• K Na2SO4 ?

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Double Replacement(Double Displacement)

• AB CD ? AD CB

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Double Replacement Reactions

• Occur in aqueous solutions
• For a DR reaction to occur one of the following
  must happen
• A precipitate is formed (an insoluble or slightly
  soluble solid).
• A molecular compound (usually water is formed).
• A gas is formed.

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Example Production of a PrecipitateSilver
Nitrate Sodium Chloride

• Precipitate
• AgCl (s)

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Solubility Rules

• See the reference chart behind your periodic
  table.

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Example Production of H2O

• H2SO4 2NaOH ? 2H2O(l) Na2 SO4