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Think about it:. 1. Whats the difference between cutting and burning a piece of wood? 2. How should the mass of the products (results of each process) compare to the original piece of wood?. AGENDA: Distinguishing and identifying changes - PowerPoint PPT Presentation

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  • Think about it:1. Whats the difference between cutting and burning a piece of wood?

    2. How should the mass of the products (results of each process) compare to the original piece of wood?

  • And how to tell the difference

    Physical and Chemical ChangesAGENDA:Distinguishing and identifying changes

    Steel wool demonstration (this will get started early in the lesson, but we will revisit it several times.

    Guided practice to distinguish changes.

    Independent practice

  • Physical ChangeSubstance may seem different, but the way the atoms combine is the same.Chemical ChangeChanges the way the atoms combine to form substances(new substances will have different physical properties)

  • Steel Wool Demonstration We will be taking observations every 5 minutes for this demonstrations

  • Its a physical change ifIt changes shape or sizeIt dissolves.It changes phase (freezes, boils, evaporates, condenses)

    Its a chemical change ifIt burnsTemperature changes without heating/coolingIt bubbles (makes a gas)It changes colorIt forms any new materialsHow are these different?

  • What kind of change is it if someone...Tears up paper?Physical changeMixes salt and water?Physical change

  • What kind of change is it if someone...Burns paper?Chemical changeEvaporates salt water?Physical change

  • What kind of change is it if someone...Mixing vinegar and baking soda?

    Chemical change

  • Guided Practice (Left Side):For each of the following examplesDecide whether the changes is chemical or physicalJustify your answer.

  • Boiling water is a physical change because the liquid water changes state to become water vapor when enough heat is added.

  • Rusting (oxidation)

    Chemcal

  • Physical or Chemical Change?Painting WoodPHYSICAL

  • Physical or Chemical Change?Burning PaperCHEMICAL

  • Physical or Chemical Change?Digestion of foodCHEMICAL

  • Physical or Chemical Change?Sugar dissolving in waterPHYSICAL

  • Physical or Chemical Change?A pond freezing in winterPHYSICAL

  • Physical or Chemical Change?Cutting wirePHYSICAL

  • Law of Conservation of MassMatter can never be created or destroyed.This means:During any physical or chemical change, the total mass of all substances before and after the change remains the same.Sometimes, measuring all the components of a change is difficult.Example: if you boiled water, it would be difficult to measure the mass of all the water vapor.

  • Temperatures influence on chemical changesThis means:During any physical or chemical change, the total mass of all substances before and after the change remains the same.

  • Time (min) Mass (g)ColorOther ObservationsRoomtemp.HotRoomtemp.HotRoom temp.Hot0

    Teachers: assign a time keeper for the demonstrations and have students assist with recording observations*Students should distinguish boiling (phase change) from creating of a new gas. Boiling water and the bubbles (carbon dioxide) released from mixing vinegar and baking soda can be used as a reference for students.

    *The following examples can be used as think-alouds to model how students should justify answer. Use of individual or group whiteboards or another type of response system can be used to check for understanding.*

    *This is the only slide from the guided practice that has a modeled justification. All other examples only state whether to the processes is a physical or chemical change.*