Reaction Types

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Reaction Types
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How do we know what will be produced in a
chemical reaction?

• Recognizing a pattern of reactivity gives a
  broader understanding than memorizing a large
  number of reactions
• Would expect elements of the same family to
  behave similar
• 2K 2H2O ? 2KOH H2
• What will happen if Na combines with water?

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Five Types of Reactions

• Combustion rapid reaction that produces flame
• Occurs in hydrocarbons (compounds of C, H, and
  sometimes O)
• Reaction of hydrocarbon with oxygen to produce
  carbon dioxide and water
• C3H8 5O2 ? 3CO2 4H2O
• 2CH3OH 3O2 ? 2CO2 4H2O

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Combination or Synthesis

• Two reactants combine to form a single product
• A B ? AB
• Examples
• C O2 ? CO2
• N2 3H2 ? 2NH3
• CaO H2O ? Ca(OH)2

5
Decomposition

• Single reactant breaks apart to form two or more
  substances
• AB ? A B
• Examples
• 2KClO3 ? 2KCl 3O2
• CaCO3 ? CaO CO2

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Single Replacement

• One element replaces another similar element in a
  compound
• A BX ? AX B
• Examples
• Fe 2HCl ? FeCl2 H2
• Zn CuSO4 ? ZnSO4 Cu
• Na 2H2O ? 2NaOH H2

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Double Replacement

• Atoms exchange partners
• Also called metathesis reactions
• AX BY ? AY BX
• We will look at two types of double replacement
• Acid-base reactions
• Precipitation reactions

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Acid-Base Reactions

• Acid substance that increases the H
  concentration in aqueous solutions
• HCl ? H Cl-
• H2SO4 ? H HSO4-
• HSO4 ? H SO42-

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Base

• Increases the OH- concentration
• NaOH ? Na OH-
• NH3 H2O ? NH4 OH-

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Neutralization

• Acids and bases react together to produce a salt
  (ionic compound) and water
• HCl NaOH ? NaCl H2O
• Write a balanced equation for the reaction of
  hydrobromic acid, HBr, with barium hydroxide,
  Ba(OH)2.

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• Write the balanced equation for the reaction
  between phosphoric acid, H3PO4, and potassium
  hydroxide.

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Precipitation Reaction

• Double replacement that forms a precipitate
• KI (aq) Pb(NO3)2 (aq) ? PbI2 (s) 2KNO3
  (aq)

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Example

• When sodium phosphate and barium nitrate are
  mixed, a precipitate of barium phosphate forms.
  Write the balanced equation.

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Example

• When aqueous sodium hydroxide and magnesium
  nitrate are mixed, a magnesium hydroxide
  precipitate forms. Write the balanced chemical
  equation.