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 • Catalyst • Chemistry Prom 2009 Day 1! • Practice and Work Time • Exit Question

Today’s Objectives • SWBAT differentiatebetween 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 • Formation of a gas • Formation of a precipitate • Temperature change • 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?

Chemistry Prom 2009! 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. • Combustion • Synthesis • Decomposition • Single-Replacement • Double-Replacement

Boom goes the dynamite! Is C50H102 a hydrocarbon? 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

Combustion ExamplesPredict products and balance • CH4(g) + O2(g)  • C2H2(g) + O2(g)  2 CO2(g) + 2 H2O(g) 2 5 4 CO2(g) + 2 H2O(g)

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

Your Turn! • Write balanced equations for the following reactions: • Methane gas (CH4) combusts. • Butene gas (C4H4) burns in the air. • 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 Geez I could use a mate. Satisfaction  Man I’m lonely

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- Al2O3 AlO

Practice A, B, and D Which reactions are synthesis reactions? C + O2 CO2 CaO + H2O  Ca(OH)2 H2O  H2 + O2 2Na + Cl2 2NaCl Fe + CuSO4  FeSO4 + Cu 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 Satisfaction! I want to see other people I don’t think this is right for us… 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 Diatomic Alert!!!! H2O  H + O H2 + O2 Don’t forget to balance!

Practice – Your Turn! • Show the decomposition of ammonium nitrate into dinitrogen monoxide and water when the reactant is heated. • Show the decomposition of NaN3.

More Practice! C, D and F Which reactions are decomposition reactions? C + O2 CO2 CaO + H2O  Ca(OH)2 H2O  H2 + O2 H2SO4 H2 + S + 2O2 Fe + CuSO4  FeSO4 + Cu 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 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 • Identify the following reactions as combustion, synthesis, or decomposition • CH4 + 2 O2 CO2 +2 H2O • 2 H2NO3 2 H2 + N2 + 3 O2 • Write the balanced chemical equation for the decomposition of solid magnesium oxide.

Catalyst – November 9+2 3 , 2009