Download - Catalyst – November 9+2 3 , 2009
Catalyst – November 9+23, 2009
What are the four ways you know a
chemical reaction has occurred?
Balance:. __Ca + __H2O
__Ca(OH)2 + __H2
Weekly Goal!
Today’s Agenda
CatalystChemistry Prom 2009 Day 1!
Practice and Work TimeExit 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 gas2. Formation of a precipitate3. Temperature change4. 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. Combustion2. Synthesis3. Decomposition4. Single-Replacement5. 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
H2OA hydrocarbon is any compound made of
only hydrogen and carbonEx: CH4, C2H4Is C50H102 a
hydrocarbon?
Combustion ExamplesPredict products and balance
1. CH4(g) + O2(g)
2. C2H2(g) + O2(g)
CO2(g) + 2 H2O(g)
4 CO2(g) + 2 H2O(g)
2
52
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 or 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. Two substances dancing alone decide
to hook up… become a happy couple A + B AB
Man I’m lonely
Geez I could use a mate.
Satisfaction
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) AlOAl3+O2-Al2O3
Practice
Which reactions are synthesis reactions?
A. C + O2 CO2
B. CaO + H2O Ca(OH)2
C. H2O H2 + O2
D. 2Na + Cl2 2NaCl
E. Fe + CuSO4 FeSO4 + Cu
F. 2K3PO4 + 3H2SO4 3K2SO4 + 2H3PO4
A, B, and D
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 don’t think this is
right for us…
I want to see other people Satisfaction!
Satisfaction!
Practice
Show the decomposition water after electricity has passed through it. What are the reactants?
Water! H2O 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
H2O H + O
Diatomic Alert!!!!
H2 + O2Don’t
forget 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
D. H2SO4 H2 + S + 2O2
E. Fe + CuSO4 FeSO4 + Cu
F. K3PO4 K3P + 2O2
C, D and F
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, 14-20C) Early Finishers: Predict what the
chemical formulas for Octene and Octyne would be. Octane is C8H18.
Part A Examples
Combustion Word Problem: Carbon tetrahydride reacts with
oxygen gas to produce carbon dioxide and water. Balanced Equation: CH4 + 2 O2 CO2 + 2 H2O
Synthesis Word Problem: Hydrogen and oxygen react to
form water. Balanced Equation: H2 + O2 H2O
Decomposition Word Problem: Water decomposes to form
hydrogen and oxygen. Balanced Equation: H2O H2 + O2
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.