Chemical Reactions and Energy. Classwork and Homework. Slide 1 / 75. Slide 2 / 75. Slide 3 / 75. Slide 4 / 75. Slide 5 / 75.

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1 Slide 1 / 75 Slide 2 / 75 New Jersey Center for Teaching and Learning Progressive Science Initiative This material is made freely available at and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Chemical Reactions and Energy Classwork and Homework Click to go to website: Slide 3 / 75 Slide 4 / 75 Term and Definition What I Remember My Questions Unit Preview Classwork Complete as much of the Graphic Organizer on the next page as you can based on what you already know. For each term you should give a definition of the term and up to three other things you remember about the term. One of your three may be an example of the term itself. Even if you don t think you have learned about the term before, you should be able to find a definition for the term. In the last column, list any questions you still have about the term. Atom Element Molecule Compound Pure Substance Slide 5 / 75 Slide 6 / 75 Term and Definition Mixture What I Remember My Questions Heterogeneous Mixture Classwork #1: Signals and Changes Homogeneous Mixture Physical Property Chemical Property

2 Slide 7 / 75 Slide 8 / 75 Complete the list of common signals that a change is occurring or has occurred. Remember, these signals are usually based on OBSERVABLE PROPERTIES. Some properties will require you to use a tool such as a thermometer or a ruler to determine how much change has occurred. The first one has been completed for you as a guide. Signal and Example Observed Using Measured Using Phase change melting candle wax melting Phase change - freezing Phase change boiling Phase change - condensing Eyes because it No special tools loses its shape and required might change color Color change Odor change Slide 9 / 75 Slide 10 / 75 Signal and Example Observed Using Measured Using Signal and Example Observed Using Measured Using Flavor change Temperature change Smoke produced Taste buds UNSAFE, NEVER TASTE ANYTHING IN THE SCIENCE LAB Mass change Volume change Light produced Density change Bubbles produced Shape change Precipitate produced Texture change Slide 11 / 75 Slide 12 / 75 Classwork #2: Classifying Physical Changes and Chemical Reactions For each situation, describe whether it is a physical change or a chemical reaction and then explain your thinking. There may be more than one correct answer depending on how you think about the situation.

3 Slide 13 / 75 Slide 14 / 75 Situation Physical or Chemical Thought Process Situation Physical or Chemical Thought Process Butter melting Physical change It is still butter. It was a phase change from solid to liquid Puddles evaporating Charcoal heating a grill Cutting your hair Mixing sugar in water Melting silver to make jewelry Heating sugar on the stove until it turns brown and starts smoking Blowing bubbles Melting cheese Digesting food Making cheese Breathing Slide 15 / 75 Slide 16 / 75 Situation Physical or Chemical Thought Process Bleaching your hair Classwork #3: Conservation of Mass Sharpening a knife Firework explodes Composting Slide 17 / 75 1 Are the laws of conservation of matter and conservation of mass interchangeable? Why or why not? Slide 18 / 75 2 Hydrogen peroxide decomposes to give water and oxyg A What part of this chemical reaction represents reactants? B What part of this chemical reaction represents products? C Explain the difference between reactants and products.

4 Slide 19 / 75 3 Is it possible to start with 25g of reactants and end with 35g of products? Why or why not? Slide 20 / 75 4 Consider the following equation: AgNO 3 + FeCl 2 AgCl +HNO Are the laws of conservation of mass and matter true in the reaction? Justify your answer. Slide 21 / 75 Slide 22 / 75 5 In order to burn something in the laboratory, oxygen gas is needed. A Where does the oxygen gas come from? B Is the oxygen gas a reactant or product. Explain. Homework: Conservation of Mass Slide 23 / 75 6 Is it possible to start with 5g of one chemical and 10g of another chemical and make 15g of a third chemical? Explain why or why not. Slide 24 / 75 7 Is conservation of mass and matter true in the reaction: AgNO 3 + HCl AgCl +HNO 3? Justify your answer.

5 Slide 25 / 75 Slide 26 / 75 8 Why is it hard to measure the amount of products produced when something burns? Classwork #4: Balancing Equations Slide 27 / 75 9 Draw a balanced picture equation to show individual iron atoms combining with individual sulfur atoms to form iron (II) sulfide, which has the formula FeS. Identify the reactants and products. Slide 28 / Draw a balanced picture equation to show individual carbon atoms combining with individual fluorine atoms to form carbon tetrafluoride which has the formula CF 4. Identify the reactants and products. Slide 29 / Use a chart to show that the following equation is balanced:n 2 + 2O 2 2NO 2 Slide 30 / Balance the following equation: Fe 2O 3 + Al Al 2O 3 + Fe A Name the reactants: B Name the products: A Name the reactants: B Name the products: C Are the properties of the products and reactants the same? Justify your answer.

6 Slide 31 / 75 Homework: Balancing Equations Slide 32 / Draw a balanced picture equation to show individual calcium atoms combining with individual phosphorus atoms to form calcium phosphide, which has the formula Ca 3P Identify the reactants and products. Slide 33 / Draw a balanced picture equation to show individual gold atoms combining with individual bromine atoms to form gold (I) bromide, which has the formula AuBr. Identify the reactants and products. Slide 34 / Use a chart to show that the following equation is balanced:cuoh + HF H 2O + CuF A Name the reactants: B Name the products: Slide 35 / 75 Slide 36 / Balance the following equation: Li 3P + Al AlP + Li A Name the reactants: B Name the products: Classwork #5: Types of Energy

7 Slide 37 / Identify an example of each type of energy in the image below. Justify your choices. Slide 38 / Which has more energy a bus moving at 15m/s or a baseball moving at 15m/s? Why? A Kinetic Energy: B Chemical Potential Energy: C Electromagnetic Energy: D Thermal Energy: Slide 39 / 75 Slide 40 / Which has more energy 5 kilograms of dynamite or 10 kilograms of dynamite? Why? Homework: Types of Energy Slide 41 / What is the major type of energy of sunlight? Why? Slide 42 / What is the major type of energy of a raindrop falling from the sky? Why?

8 Slide 43 / What has more kinetic energy 10kg of bees flying at 10m/s or 10kg of birds flying at 10m/s? Why? Slide 44 / Which has more energy 100 calories of cookies or 100 calories of popcorn? Why? Slide 45 / 75 Slide 46 / 75 Classwork #6: Energy Changes Use the word/phrase bank below to fill in the Venn diagram. After using all the words in the word bank, come up with two new examples of each type of reaction and write these in the appropriate place on the Venn diagram. Baking bread Conserve mass Reactants have lower energy than products Chemical reaction Absorb energy from surroundings Conserve energy Burning a candle Melting ice cubes Heats surroundings Reactants have higher energy than products Slide 47 / 75 Slide 48 / 75 Endothermic Exothermic Homework: Energy Changes

9 Slide 49 / Define exothermic reactions. Slide 50 / Define endothermic reactions. Slide 51 / Is boiling water an endothermic or exothermic process? Justify your answer. Slide 52 / Is lighting a match an endothermic or exothermic process? Justify your answer. Slide 53 / 75 Slide 54 / Is baking a cake an endothermic or exothermic process? Justify your answer. Classwork #7: Temperature and Thermal

10 Slide 55 / If you know an object s temperature, do you know how much thermal energy it has? Explain. Slide 56 / What properties of a substance influence the amount of thermal energy it possesses? Slide 57 / Which has more thermal energy, 500mL of boiling water or 250mL of boiling water? Explain your answer. Slide 58 / What must happen to the thermal energy of a substance during deposition? Explain why. Slide 59 / 75 Slide 60 / What must happen to the thermal energy of a substance during evaporation? Explain why. Homework: Temperature and Thermal

11 Slide 61 / Explain how two substances can be at the same temperature but have different amounts of thermal energy. Give an example. Slide 62 / Explain how two substances can be at different temperatures but still have the same amount of thermal energy. Give an example. Slide 63 / Which has more thermal energy, 500g of ice or 500g of steam? Explain your answer. Slide 64 / What must happen to the thermal energy of a substance during freezing? Explain why. Slide 65 / 75 Slide 66 / What must happen to the thermal energy of a substance during melting? Explain why. Classwork #8: Energy Flow

12 Slide 67 / Explain when heat transfers between two objects. Slide 68 / For the following scenarios, explain which objects or substances gain energy and which lose energy: A Bread baking in an oven B Ice forming in a freezer C Melting Ice Cream D Burning your hand on a hot stove Slide 69 / Two chocolate cakes are baking in an oven though one cake is much larger than the other. Slide 70 / Explain what happens when you put a cold pan in a hot oven with respect to energy. A In which direction must heat flow in order to bake the cakes? B If both cakes reach a temperature of 400 F, what can you say about the amount of energy transferred for the large cake versus the smaller cake? Slide 71 / 75 Slide 72 / When does heat transfer between two objects stop? Homework: Energy Flow

13 Slide 73 / Explain how size affects heat transfer. Slide 74 / Why does water evaporate quickly in a patch of sunny sidewalk and more slowly on a patch of sidewalk in the shade? Slide 75 / Your friend touches an ice cube and it melts under his finger. He wonders why, his finger feels so cold when he touches the ice if he is hot enough to melt it? Explain to your friend what is happening when he touches the ice in terms of heat and energy transfer.