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Catalyst – September_ 7_1+1_ 2009

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					                                Objectives
       SWBAT Differentiate between synthesis, decomposition and
        combustion reactions
       SWBAT Predict the products of Synthesis, decomposition and
        combustion reactions

                                   Catalyst
       Balance the following reaction:
         C2H2 + O2  CO2 + H2O
       What are some ways that you can tell a chemical reaction has
        occurred?
Today’s Agenda

 Catalyst
 Chemistry Prom 2009 Day 1!

 Practice and Work Time

 Exit Question
Today’s Objectives

 SWBAT differentiate between
  combustion, synthesis, and decomposition
  reactions.
 SWBAT predict the products of
  combustion, synthesis, and decomposition
  reactions.
Is this an example of a chemical
reaction?




 How do you know?
Evidence of Chemical Reactions

1.   Formation of a gas
2.   Formation of a precipitate
3.   Temperature change
4.   Color change
Questions from Friday

 SCENARIO: Juan wanted to see what
  would happen if he mixed water and
  salt together. After adding the salt
  and stirring, he observed that the salt
  seemed to disappear.
 QUESTION: Did a chemical reaction

  occur?
Questions from Friday

 SCENARIO: Jayde is interested in
  learning about two compounds, silver (I)
  nitrate and sodium chloride. She
  decides to dissolve each compound in
  water and mix them. When she does
  this, she sees a white solid form.
 QUESTION: Did a chemical reaction

  occur?
Questions from Friday

 SCENARIO: Antoinette puts 2 grams of
  salt into a beaker filled with a clear
  unknown liquid. The salt appears to
  disappear into the liquid.
 QUESTION: Did a chemical reaction

  occur?
Questions from Friday

 SCENARIO: William was curious about
  what would happen if he mixed zinc
  and hydrochloric acid. After doing so,
  the mixture bubbles and fizzes.
 QUESTION: Did a chemical reaction

  occur?
Combustion, Synthesis, and
Decomposition Reactions
Combustion, Synthesis,
 and Decomposition
     Reactions
Chemical Reactions

    There are 5 types of chemical hook-
     ups (reactions) at the prom this year.
    1.   Combustion
    2.   Synthesis
    3.   Decomposition
    4.   Single Replacement
    5.   Double-replacement
Boom goes the dynamite!

Key Point #1: A combustion reaction is
 when a hydrocarbon burns in the
 presence of oxygen, releasing heat
 and light
  The   products will ALWAYS be CO2 and H2O
   A  hydrocarbon is any compound made of only
     hydrogen and carbon
    Ex: CH4, C2H4


               Is C50H102 a
               hydrocarbon?
Combustion Examples
Predict products and balance
1.    CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g)


2.   2C2H2(g) +5 O2(g) 4 CO2(g) + 2 H2O(g)
    Practice
    Write the chemical reaction for ethane
     gas (C2H6) burning in air.
    1.   If you see the word “BURNING,” that means it
         is a combustion reaction.
    2.   What are the reactants?
           C2H6 and O2
    3.   What are the products?
           CO2 and H2O
    4.   Last step: Balance! (don’t worry about
         phases for now)
         C2H6 + O2  CO2 + H2O
Your Turn!

    Write balanced equations for the
     following reactions:
1.   Methane gas (CH4) combusts.
2.   Butene gas (C4H4) burns in the air.
3.   Ethyne gas (C2H2) goes through a
     combustion reaction.
Let’s come together

Key Point #2: A synthesis reaction
 is one in which two more
 substances combine to form one
 new substance.
 A   + B  AB
  Two substances are at the Prom, dancing
   alone…they decide to hook up…
Let’s come together….

   Synthesis reaction – two more substances
    combine to form one new substance.
     Twosubstances dancing alone decide to hook up…
     become a happy couple
   A + B  AB


      Man I’m       Geez I            Satisfaction 
       lonely      could use
                    a mate.
    Practice

   Show the synthesis of solid aluminum and oxygen gas.
     What    are the reactants?
       Al + O2 (DIATOMIC ALERT!!!!)
     What are the products?
       It’s a synthesis reaction, so we know Al and O are going to
        make a compound….
       If the products aren’t in the question you need to KRISS
        KROSS TO figure them out!


        Al (s) + O2 (g)                  Al3+O2-
                                           AlO
                                          Al 2O3
Practice

    Which reactions are synthesis reactions?
A.   C + O2  CO2
B.   CaO + H2O  Ca(OH)2A, B, and D
C.   H2O  H2 + O2
D.   2Na + Cl2  2NaCl
E.   Fe + CuSO4  FeSO4 + Cu
F.   2K3PO4 + 3H2SO4  3K2SO4 +
     2H3PO4
I don’t think this is working out…

Key Point #3: A decomposition
 reaction is one in which one substance
 breaks down into multiple substances,
 usually with the help of some kind of
 heat or energy
  AB   A+B
  A   couple at the Prom decides to break up
     I don’t think this is working out…

           Decomposition reaction – one substance breaks
            into multiple substances
            A   couple decides…well it is time to break up
           AB  A + B

                       I want to see                    Satisfaction!
I don’t think
 this is right         other people
                                       Satisfaction!
   for us…
    Practice

   Show the decomposition water after electricity has
    passed through it.
     What    are the reactants?
       Water! H2O
                                  Diatomic Alert!!!!
     What are the products?
       It’s a decomposition reaction, so we know the elements in
        water are going to break apart
       The question will specify if any compounds are formed


                                                     Don’t forget
        H2O  H2+ O 2
                 +O                                  to balance!
Practice – Your Turn!

1.   Show the decomposition of
     ammonium nitrate into dinitrogen
     monoxide and water when the
     reactant is heated.
2.   Show the decomposition of NaN3.
More Practice!

    Which reactions are decomposition reactions?
A.   C + O2  CO2
B.   CaO + H2O  Ca(OH)2
C.   H2O  H2 + O2          C, D and F
D.   H2SO4 H2 + S + 2O2
E.   Fe + CuSO4  FeSO4 + Cu
F.   K3PO4  K3P + 2O2
Work Time – 3 Parts

A) Write one word problem and
 balanced chemical equation for each
 type of reaction (combustion, synthesis,
 decomposition)
  Examples    of Hydrocarbons:
    Propane (C3H8), Propene (C3H4), Propyne (C3H2)
    Pentane (C5H12), Pentene (C5H10), Pentyne (C5H8)

B) Book work: Pg 285, 14-20
C) Early Finishers: Predict what the
  chemical formulas for Octene and
Exit Question

1. Identify the following reactions as
   combustion, synthesis, or decomposition
   CH4 + 2 O2  CO2 +2 H2O
   2 H2NO3  2 H2 + N2 + 3 O2
2. Write the balanced chemical equation
   for the decomposition of solid
   magnesium oxide.

				
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