Types of Chemical Reactions

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Types of Chemical Reactions
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Types of Reactions

• We will talk about five types of chemical
  reactions
• Synthesis reactions
• Decomposition reactions
• Single displacement reactions
• Double displacement reactions
• Combustion reactions
• You need to be able to identify the type of
  reaction and predict the product(s)

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1. Synthesis Reactions

• two substances (generally elements) combine and
  form a compound
• reactant reactant ? 1 product
• A B ? AB
• Example carbon oxygen ? carbon dioxide
• C O2 ? CO2

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Synthesis Reactions
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Practice

• Predict the products. Write and balance the
  following synthesis reaction equation.
• Sodium metal reacts with chlorine gas
• Na(s) Cl2(g) ? NaCl(s)

2Na (s) Cl2 (g) ? 2NaCl (s)
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2. Decomposition Reactions

• occur when a compound breaks up into the elements
  or into a few simpler compounds
• reactant ? product product
• AB ? A B
• Example water ? hydrogen oxygen
• H2O ? H2 O2
• 2 H2O ? 2H2 O2

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Decomposition Reactions
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Practice

• Predict the products. Write and balance the
  following decomposition reaction equation
• Lead (IV) oxide decomposes

PbO2 (s) ? Pb (s) O2 (g)
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3. Single Displacement Reactions

• occur when one element replaces another in a
  compound.
• element compound? product product
• A BC ? AC B (if A is a metal) OR
• A BC ? BA C (if A is a non-metal)
• (note the cation always goes first!)

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A BC ? AC B
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Single Displacement Reactions
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Practice

• Write and balance the following single
  replacement reaction equation
• Zinc metal reacts with hydrochloric acid
  (hydrogen monochloride), hint Zinc has a 2
  charge
• Skeleton Zn HCl ?
• Balanced Zn 2HCl ? ZnCl2 H2

ZnCl2 H2
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4. Double Displacement Reactions

• occur when a metal replaces a metal in a compound
  and a nonmetal replaces a nonmetal in a compound
• compound compound ? product product
• AB CD ? AD CB

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Double Displacement Reactions

• first and last ions go together, inside ions go
  together
• Example silver nitrate and sodium chloride
• AgNO3(aq) NaCl(s) ? AgCl(s) NaNO3(aq)
• Example potassium sulfate and barium nitrate
• K2SO4(aq) Ba(NO3)2(aq) ? 2KNO3(aq) BaSO4(s)

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Neutralization Reaction

• This is a special type of Double Replacement
  Reactions
• KOH(aq) HCl(aq) ? H2O(l) KCl(aq)
• Notice that water (a neutral fluid) and an ionic
  compound is produced from the reaction of an acid
  and a base.
• What was the pH of the solution made?
• pH7

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5. Combustion Reactions

• occur when a hydrocarbon reacts with oxygen gas.
• always forms carbon dioxide and water vapour as
  products

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Combustion Reactions

• Hydrocarbon Oxygen ? CO2 H2O Energy
• incomplete burning may result in undesirable
  by-products like carbon monoxide

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Edgar Allen Poes drooping eyes and mouth are
potential signs of CO poisoning
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Combustion

• Example combustion of pentane

• C5H12 (l) 8O2 (g) ? 5CO2 (g) 6H2O (g)