New Jersey Center for Teaching and Learning Slide 1 / 75 Progressive Science Initiative This material is made freely available at www.njctl.org 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. Click to go to website: www.njctl.org Slide 2 / 75 Chemical Reactions and Energy Classwork and Homework www.njctl.org Slide 3 / 75 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.
Term and Definition What I Remember My Questions Slide 4 / 75 Atom 1. 2. 3. Element 1. 2. 3. Molecule 1. 2. 3. Compound 1. 2. 3. Pure Substance 1. 2. 3. Term and Definition What I Remember 1. My Questions Slide 5 / 75 Mixture 2. 3. 1. Heterogeneous Mixture 2. 3. 1. Homogeneous Mixture 2. 3. 1. Physical Property 2. 3. 1. 2. Chemical Property 3. Slide 6 / 75 Classwork #1: Signals and Changes
Slide 7 / 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. Slide 8 / 75 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 Signal and Example Observed Using Measured Using Slide 9 / 75 Flavor change Taste buds UNSAFE, NEVER TASTE ANYTHING IN THE SCIENCE LAB Temperature change Smoke produced Light produced Bubbles produced Precipitate produced
Slide 10 / 75 Signal and Example Observed Using Measured Using Mass change Volume change Density change Shape change Texture change Slide 11 / 75 Classwork #2: Classifying Physical Changes and Chemical Reactions Slide 12 / 75 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.
Situation Physical or Chemical Thought Process Slide 13 / 75 Butter melting Physical change It is still butter. It was a phase change from solid to liquid Charcoal heating a grill Mixing sugar in water Heating sugar on the stove until it turns brown and starts smoking Digesting food Breathing Slide 14 / 75 Situation Puddles evaporating Cutting your hair Physical or Chemical Thought Process Melting silver to make jewelry Blowing bubbles Melting cheese Making cheese Slide 15 / 75 Situation Physical or Chemical Thought Process Bleaching your hair Sharpening a knife Firework explodes Composting
Slide 16 / 75 Classwork #3: Conservation of Mass 1 Are the laws of conservation of matter and conservation of mass interchangeable? Why or why not? Slide 17 / 75 2 Hydrogen peroxide decomposes to give water and oxyg Slide 18 / 75 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.
3 Is it possible to start with 25g of reactants and end with 35g of products? Why or why not? Slide 19 / 75 4 Consider the following equation: Slide 20 / 75 AgNO 3 + FeCl 2 AgCl +HNO 3. Are the laws of conservation of mass and matter true in the reaction? Justify your answer. 5 In order to burn something in the laboratory, oxygen gas is needed. Slide 21 / 75 A Where does the oxygen gas come from? B Is the oxygen gas a reactant or product. Explain.
Slide 22 / 75 Homework: Conservation of Mass 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 23 / 75 7 Is conservation of mass and matter true in the reaction: AgNO 3 + HCl AgCl +HNO 3? Justify your answer. Slide 24 / 75
8 Why is it hard to measure the amount of products produced when something burns? Slide 25 / 75 Slide 26 / 75 Classwork #4: Balancing Equations 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 27 / 75
10 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 28 / 75 11 Use a chart to show that the following equation is balanced:n 2 + 2O 2 2NO 2 Slide 29 / 75 A Name the reactants: B Name the products: C Are the properties of the products and reactants the same? Justify your answer. 12 Balance the following equation: Fe 2O 3 + Al Al 2O 3 + Fe Slide 30 / 75 A Name the reactants: B Name the products:
Slide 31 / 75 Homework: Balancing Equations 13 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 2. Identify the reactants and products. Slide 32 / 75 14 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 33 / 75
15 Use a chart to show that the following equation is balanced:cuoh + HF H 2O + CuF Slide 34 / 75 A Name the reactants: B Name the products: 16 Balance the following equation: Li 3P + Al AlP + Li Slide 35 / 75 A Name the reactants: B Name the products: Slide 36 / 75 Classwork #5: Types of Energy
17 Identify an example of each type of energy in the image below. Justify your choices. Slide 37 / 75 A Kinetic Energy: B Chemical Potential Energy: C Electromagnetic Energy: D Thermal Energy: 18 Which has more energy a bus moving at 15m/s or a baseball moving at 15m/s? Why? Slide 38 / 75 19 Which has more energy 5 kilograms of dynamite or 10 kilograms of dynamite? Why? Slide 39 / 75
Slide 40 / 75 Homework: Types of Energy 20 What is the major type of energy of sunlight? Why? Slide 41 / 75 21 What is the major type of energy of a raindrop falling from the sky? Why? Slide 42 / 75
22 What has more kinetic energy 10kg of bees flying at 10m/s or 10kg of birds flying at 10m/s? Why? Slide 43 / 75 23 Which has more energy 100 calories of cookies or 100 calories of popcorn? Why? Slide 44 / 75 Slide 45 / 75 Classwork #6: Energy Changes
Slide 46 / 75 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 Endothermic Exothermic Slide 48 / 75 Homework: Energy Changes
24 Define exothermic reactions. Slide 49 / 75 25 Define endothermic reactions. Slide 50 / 75 26 Is boiling water an endothermic or exothermic process? Justify your answer. Slide 51 / 75
27 Is lighting a match an endothermic or exothermic process? Justify your answer. Slide 52 / 75 28 Is baking a cake an endothermic or exothermic process? Justify your answer. Slide 53 / 75 Slide 54 / 75 Classwork #7: Temperature and Thermal
29 If you know an object s temperature, do you know how much thermal energy it has? Explain. Slide 55 / 75 30 What properties of a substance influence the amount of thermal energy it possesses? Slide 56 / 75 31 Which has more thermal energy, 500mL of boiling water or 250mL of boiling water? Explain your answer. Slide 57 / 75
32 What must happen to the thermal energy of a substance during deposition? Explain why. Slide 58 / 75 33 What must happen to the thermal energy of a substance during evaporation? Explain why. Slide 59 / 75 Slide 60 / 75 Homework: Temperature and Thermal
34 Explain how two substances can be at the same temperature but have different amounts of thermal energy. Give an example. Slide 61 / 75 35 Explain how two substances can be at different temperatures but still have the same amount of thermal energy. Give an example. Slide 62 / 75 36 Which has more thermal energy, 500g of ice or 500g of steam? Explain your answer. Slide 63 / 75
37 What must happen to the thermal energy of a substance during freezing? Explain why. Slide 64 / 75 38 What must happen to the thermal energy of a substance during melting? Explain why. Slide 65 / 75 Slide 66 / 75 Classwork #8: Energy Flow
39 Explain when heat transfers between two objects. Slide 67 / 75 40 For the following scenarios, explain which objects or substances gain energy and which lose energy: Slide 68 / 75 A Bread baking in an oven B Ice forming in a freezer C D Melting Ice Cream Burning your hand on a hot stove 41 Two chocolate cakes are baking in an oven though one cake is much larger than the other. Slide 69 / 75 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?
42 Explain what happens when you put a cold pan in a hot oven with respect to energy. Slide 70 / 75 Slide 71 / 75 Homework: Energy Flow 43 When does heat transfer between two objects stop? Slide 72 / 75
44 Explain how size affects heat transfer. Slide 73 / 75 45 Why does water evaporate quickly in a patch of sunny sidewalk and more slowly on a patch of sidewalk in the shade? Slide 74 / 75 46 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. Slide 75 / 75