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Think about it:

Explore the differences between cutting and burning wood, and learn how the mass of the products compares to the original piece. This lesson includes a steel wool demonstration and guided and independent practice to distinguish between physical and chemical changes.

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Think about it:

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Presentation Transcript

  1. Think about it: 1. What’s 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?

  2. AGENDA: 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 and Chemical Changes And how to tell the difference

  3. Chemical Change PhysicalChange • Changes the way the atoms combine to form substances (new substances will have different physical properties) • Substance may seem different, but the way the atoms combine is the same.

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

  5. It’s a chemical change if It’s a physical change if • It changes shape or size • It dissolves. • It changes phase (freezes, boils, evaporates, condenses) • It burns • Temperature changes without heating/cooling • It bubbles (makes a gas) • It changes color • It forms any new materials How are these different?

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

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

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

  9. Guided Practice (Left Side):For each of the following examples • Decide whether the changes is chemical or physical • Justify your answer.

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

  11. Rusting (oxidation) Chemcal

  12. Physical or Chemical Change? • Painting Wood • PHYSICAL

  13. Physical or Chemical Change? • Burning Paper • CHEMICAL

  14. Physical or Chemical Change? • Digestion of food • CHEMICAL

  15. Physical or Chemical Change? • Sugar dissolving in water • PHYSICAL

  16. Physical or Chemical Change? • A pond freezing in winter • PHYSICAL

  17. Physical or Chemical Change? • Cutting wire • PHYSICAL

  18. Law of Conservation of Mass Matter 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.

  19. Temperatures influence on chemical changes As with the steel wool demonstration, adding energy in the form of heat typically speeds up the change. This means: During any physical or chemical change, the total mass of all substances before and after the change remains the same.

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