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12/8 - 8 th Grade Agenda Learning Objective: Learn about Fire Safety Collect HW: Reading & Notetaking: p.117 – 118 Textbook Reading p. 237-245 HW: Reading & Notetaking p.119 – 122 Reminder HW: Science Fair Background due 1/14 & 1/15 (10 Points)
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Daily Reflection Prompt: What is the difference between an exothermic and endothermic reaction?
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What is Conservation of Mass? The total mass of the reactant must equal the total mass of the products During a chemical reaction, matter is not created or destroyed
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Open End vs Closed End systems
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What is a coefficient 2 H 2 + O 2 2 H 2 O The number in front of a chemical formula in a chemical is called an coefficient It tells you how many molecules or atoms of each reactant or product take part in the reaction
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What is a Chemical Equation Reactant + Reactant Product + Product H 2 + O 2 H 2 O 2 Subscript shows the number of atoms of an element in a molecule
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Balancing Equation
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Types of Chemical Reactions What is a Synthesis? When two or more substances (elements or compounds) combine to make a more complex substance, the process is called a synthesis
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Types of Chemical Reactions What is Decomposition? Decomposition reaction breaks down compounds into simpler products
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What is a Replacement reaction? It is similar to a girl switching boyfriends A reaction in which one element replaces another in a compound
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What is an activation energy? The minimum amount of energy that has to be added to start a reaction. Think of a chemical reaction as being like a rock resting behind a ridge at the top of a hill.
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Energy in Chemical Reactions Every chemical reaction involves a change of energy. (In the test)
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What affects the rate of chemical reactions? Concentration Surface Area Temperature Catalysts
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What is a Catalyst? A Material that increases the rate of a chemical reaction by lowering the activation energy What does it mean?
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Catalyst Demonstration Paper clips represents reactants If I place two paper clips in a cup, no matter how hard I shake the cup, I can not get the paper clips to link up.
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Catalyst Demonstration In this model, Paper clip = Reactant Dollar bill = Catalyst
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Another Catalyst Demonstration Hydrogen Peroxide decomposes into Water and Oxygen slowly 2H 2 O 2 -> 2H 2 O + O 2 Yeast acts as a Catalyst and speeds up the reaction.
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What is an enzyme or catalyst? Enzyme is biological catalyst which provide a surface on which reactions take place. This helps reactions happen at lower temperatures because it lowers activation energy.
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What is combustion? Combustion is a rapid reaction between oxygen and a substance called a fuel.
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What are the three things necessary to start and maintain a fire? Fuel Oxygen Heat
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What are four common sources of fires at home? Small heaters Fires in the kitchen Faulty electric wiring Carelessness with cigarettes.
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How can you fight a fire? A. Blow air on it? B. Cover it with baking soda? C. Use a fire extinguisher? D. Pour water on it?
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Which of the following is a safety aid in a fire safe home. A) smoke detectors B) gasoline can in the basement C) Fire extinguishers D) Box of baking soda in the kitchen
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