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Wednesday, October 15th, 2014 Get your homework out. Homework ◦ Identify the products and reactants for the chemical equations on your HW Write P or R ◦ Define the vocabulary words during class Do Now 1. How are physical changes different from chemical changes? 2. Describe what happens to the mass of matter before and after a physical or chemical change? SWBAT read a chemical equation by identifying the products and reactants. SWBAT describe the law of conservation of mass. Essential Question What is the law of conservation of mass and what does it tell scientists about the reactants and products of a chemical equation? 1. 2. 3. 4. 5. 6. Baking soda in balloon Vinegar in flask Place balloon on flask Measure mass Dump baking soda into flask Measure mass Before ◦ What do you expect will happen? ◦ What will the mass be? After ◦ What are your observations? ◦ Why did this happen? The law of conservation of mass ◦ Mass cannot be created or destroyed ◦ Draw a picture Product Reactant Coefficient Subscript 1. 2. 3. 4. 5. Answer the 3 questions on the back of the reading on a sheet of lined paper. When you are finished answering the questions identify the reactants, products, and coefficients of the 5 chemical equations You can work with the people at your table. You have 20 minutes to complete this activity. When you finish complete the vocabulary and start the HW 1. What information does a chemical equation provide? Chemical reactions tell us what substances are reacting (being used up) and what substances are being produced (those being made). Chemical reactions also tell us the ratios of the chemicals reacting and being produced and the numbers each atom in the reaction. 2. What are reactants and products? How can reactants and products be identified? Reactants are the chemicals that are being used up. Products are chemicals that are being made. The reactants are always on the left side of the arrow. The products are always on the right side of the arrow. 3. What are coefficients? Why are coefficients important? Coefficients are the numbers in front of the formulas. Coefficients are important because they give us the number of molecules that react in a reaction. With the coefficients we know the amount of 1 substance will react with another substance 1) Zn + 2 HCl --> ZnCl2 + H2 (Zn – 2, Cl – 2, H – 2) Reactants Products 2) 2 KClO3 --> 2 KCl + 3 O2 (K – 2, Cl – 1, O – 6) Reactants Products 3) S8 + 24 F2 --> 8 SF6 (S – 8, F – 48) Reactants Products 4) 4 Fe + 3 O2 --> 2 Fe2O3 (Fe – 4, O – 6) Reactants Products 5) 2 C2H6 + 7 O2 --> 4 CO2 + 6 H2O (C–4, H–12, O-14) Reactants Products Reactant ◦ A substance that exists before a chemical reaction. Product ◦ A substance that forms as a result of a chemical reaction. Lets go back to the demonstration NaHCO3 + HC2H3O2 NaC2H3O2 + H2O + CO2 Reactants Products Number of atoms: Na H C O 1 5 3 5 What is the law of conservation of mass and what does it tell scientists about the reactants and products of a chemical equation? Identify the reactants and products of the following chemical equation. Identify the number of atoms of each element on each side of the chemical equation. 1. FeS + 2HCl H2S + FeCl2 Reactants: Products: # of atoms: # of atoms: 2. What is the law of conservation of mass? Identify the reactants and products of the following chemical equations. 1. FeS + 2HCl H2S + FeCl2 Reactants: FeS, HCl # of atoms: Fe-1, S-1, H-2, Cl-2 Products: H2S, FeCl2 # of atoms: Fe-1, S-1, H-2, Cl-2 2. What is the law of conservation of mass? • Mass cannot be created or destroyed. • Mass before a physical or chemical change will be the same as after the change.