Reaction Types Chapter 10

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Reaction TypesChapter 10
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Objectives

• Identify the reactants and products in a chemical
  equation
• From the word equation for a chemical reaction,
  write and balance the formula equation for the
  reaction
• Identify a chemical reaction as one of the five
  major reaction types

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Reaction Types

• There are 5 basic reaction types
• Synthesis
• Decomposition
• Single Replacement
• Double Replacement
• Organic Combustion

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Synthesis

• In a synthesis reaction, one compound forms from
  2 or more simpler reactants
• i.e. A B ? AB
• The reactants can be either elements or compounds
  
• E.g. C2H4(g) H2O(g) ? C2H5OH(g)
• Is this balanced?
• E.g. H2(g) O2(g) ? H2O(l)
• Is this balanced?

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Decomposition

• In a decomposition reaction, a compound breaks
  down into 2 or more simpler products
• i.e. AB ? A B
• An external energy source is usually required for
  these reactions to occur
• E.g. heat, light, electricity
• A ternary acid will decompose to yield water and
  a nonmetallic oxide.
• E.g. H2C03 ? CO2 H20 Is this balanced?
• Ammonium carbonate decomposes into ammonia,
  carbon dioxide, and water
• i.e. (NH4)2CO3 ? NH3 CO2 H20 Is this
  balanced?

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Additional Decomposition Examples

• E.g. CaCO3(s) ? CaO(s) CO2(g)
• Is this balanced?
• E.g. NH4NO3(s) ? N2(g) H2O(g) O2(g)
• Is this balanced?
• E.g. H2O(l) ? H2(g) O2(g)
• Is this balanced?

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Single Displacement

• In a Single Displacement reaction, one partner
  switches in an aqueous solution
• i.e. AX B ? A BX

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Single Displacement with Metals
AX B ? A BX

• The replacing metal (B) can only switch if it is
  more active than the original metal (A).
• E.g. Cu AgNO3 ? Cu(NO3)2 Ag
• Metals which are more active than hydrogen will
  replace hydrogen from acids to form a salt and
  hydrogen gas.
• E.g. HCl Mg ? MgCl2 H2 Is this
  balanced?
• Very active metals react with water to form a
  base and hydrogen gas.
• E.g. Na H2O ? NaOH H2 Is this balanced?

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Single Displacement with Nonmetals
AX B ? A BX

• Nonmetals will take the place of the ion in the
  compound which has a negative charge
• The nonmetal must be more active than the
  nonmetal which it replaces.
• E.g. Na H2O ? NaOH H2
• Is this balanced?

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Single Displacement (Cont)
AX B ? A BX

• To predict the products
• Separate the reactants into their respective ions
• Move the anion to the other cation to form
  Product 1
• Determine whether Product 2 (the leftover cation)
  is monatomic or diatomic
• Balance the resulting equation
• E.g. Zn(s) HCl(aq) ? ZnCl2(aq) H2(g)
• Is this balanced?
• E.g. Zn(s) CuCl2(aq) ? ZnCl2(aq) Cu(s)
• Is this balanced?

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Double Displacement

• In a Double Displacement reaction, two aqueous
  solutions react to form a precipitate and an
  aqueous solution. Both partners switch.
• i.e. AX(aq) BY(aq) ? AY(s) BX(aq)
• AY would be the precipitate in this case

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Double Displacement Predicting the Products

• Separate the reactants into their respective ions
• Put the anion of Reactant 2 with the cation of
  Reactant 1 to form Product 1
• Put the anion of Reactant 1 with the cation of
  Reactant 2 to form Product 2
• Determine which product will form the precipitate
  and label it (s)
• Balance the resulting equation

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Double Displacement Examples

• E.g. BaCl2(aq) Na2SO4(aq) ? BaSO4(s) NaCl(aq)
  
• Is this balanced?
• E.g. AgNO3(aq) NaCl(aq) ? AgCl(s) NaNO3(aq)
• Is this balanced?

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Organic Combustion

• In an organic combustion reaction, an organic
  compound, usually a carbohydrate, reacts with
  oxygen to form carbon dioxide, water vapor, heat,
  and light.
• i.e. CxHyOz O2 ? CO2 H2O Heat Light
• E.g. CH4 O2 ? CO2 H2O
• Is this balanced?
• E.g. C2H6 O2 ? CO2 H2O
• Is this balanced?

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Homework!

• Study balancing equations tonight and do the
  reaction types homework.
• Balancing Equations Quiz tomorrow, discuss
  reaction types homework, begin predicting the
  products lecture