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Properties, Changes & Types

MATTER. Properties, Changes & Types. 3/9 Physical vs. chemical changes. IQ: Match each substance with its phys. and chem. Properties: Substance Phys. Prop. Chem. Prop. Iron Wood Helium Red food coloring

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Properties, Changes & Types

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  1. MATTER Properties, Changes & Types

  2. 3/9 Physical vs. chemical changes IQ: Match each substance with its phys. and chem. Properties: SubstancePhys. Prop. Chem. Prop. • Iron • Wood • Helium • Red food coloring Properties: flammable, malleable, reacts with oxygen to form rust, reacts with bleach and loses color, grainy texture, non-flammable, less dense than air, red color

  3. 3/17 Physical and Chemical Changes IQ: Complete yellow half sheet.

  4. Physical Changes: • A physical change in a substance doesn't change what the substance is. Itssize, shape, or phase may be changed. • The substance maintains its original properties. • For example, if a piece of paper is cut up into small pieces it stillispaper. This would be a physical change in the shape and size of the paper.

  5. Water turning into steam, is still water, its just a change in phase Dissolving koolaid powder in water is a physical change.

  6. Physical Change

  7. Physical changes can be reversed. • All phase changes are physical.A cup of water can be frozen when cooled and then can be returned to a liquid form when heated. However, it’s still water the whole time. • Creating and separating mixtures are physical changes. If one decided to mix sugar into water to make sugar water, this would be a physical change as the water could be left out to evaporate and the sugar crystals would remain.

  8. What changes so it’s a physical change- Shape, size, phase, location • Melting chocolate • Water eroding rocks • Mixing cocoa powder in milk • Raining • Rubbing alcohol evaporating • Building a snowman

  9. Chemical Changes: • In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed. • The properties of the new substance are completely different than the original substances. • Chemical changes cannot be reversed with the substance changed back without special means, if at all.

  10. For example, if a piece of paper is burned, it is broken up into different substances that are not paper, and the paper cannot be brought back. Animation

  11. Some signs of chemical changes taking place • Burning • Color Changes • Fizzing sound • Bubbling or foaming (gas produced) • Producing Heat, Light, smoke, or Odor Match demo

  12. Ex. • Foaming antacid tablet • Wood burns • Rusting/Tarnishing/corroding • Cooking • Food going bad • Food being digested • Bleaching fabric

  13. OQ: Record all signs that a burning match is a chemical change.

  14. If one made a recipe for a cake with flour, water, sugar and other ingredients and baked them together, it would take extraordinary means to separate the various ingredients out to their original form.

  15. When heat is given off (exits) in a chemical change or reaction, it is called an exothermic reaction. Surroundings or container get hot. Ex. Burning wood. • When heat is absorbed in a chemical change or reaction, it is called an endothermic reaction.Surroundings or container will get cooler.

  16. Answer on a separate half sheet AND TURN IN Two clear liquids at room temperature (about 23°C) were combined in a flask. At first, there were bubbles; then, white flakes appeared at the bottom of the flask. After five minutes, the temperature of the solution was 35°C. A portion of the solution was used to measure its density and boiling point, which were determined to be 4.5 g/L and 82°C, respectively. -Did a physical or chemical change occur? Provide at least 3 pieces of evidence.

  17. Extra Credit!!!! At home add about 1 tsp. vinegar to a quarter cup of warm milk and stir. Record observations. Is it a physical or chemical change? Justify.

  18. Chemical and physical changes

  19. Physical Change • A Physical change is a change in a substance that does not change what the substance is.

  20. Physical Change - examples • Examples of physical change include: • Change in shape • Change in size • Change in phase • Melting (solid to liquid) • Boiling (liquid to gas) • Evaporation (liquid to gas) • Condensation (gas to liquid) • Freezing (liquid to solid) • Sublimation (solid to gas) • Deposition (gas to solid)

  21. Physical Change • Physical changes might be caused by: • Grinding • Cutting • Crushing • Bending • Breaking • Heating/cooling • (change in phase) • squishing

  22. Physical Change • Evidence that a physical change has occurred might include: • Change in shape • Change in form • Change in size • Change in phase (This is always a physical change!) • Physical changes are usually reversible

  23. Physical change • What could you do to these items to cause a physical change to occur?

  24. Chemical change • A chemical change is a change in which a substance is changed into a different substance. (You’ve changed what it is.)

  25. Chemical change • Examples of chemical changes include: • Burning • Rusting • Tarnishing • Decomposing • Polymerization

  26. Chemical change • Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form.

  27. Chemical change – Chemical reactions • There are 5 types of chemical reactions that cause chemical changes to occur.

  28. Chemical change – Chemical reactions • 1- Composition reactions • Two things come together to form something new • A + B = AB • 2H2 + O2 2H2O

  29. Chemical change – Chemical reactions • 2- Decomposition reactions • 1 thing breaks apart to form 2 or more things. • AB = A + B • 2H2O  2H2 + O2

  30. Chemical change – Chemical reactions • 3- Single replacement reactions • One atom replaces another atom • A + BC = AC + BorA + BC = AB + C • Mg + 2HCl  H2 + MgCl2

  31. Chemical change – Chemical reactions • Double replacement reactions • Two chemicals switch places • AX + BY = AY + BX • 2KI + Pb(NO3)2 PbI2 + 2KNO3

  32. Chemical change – Chemical reactions • Combustion reaction • A substance combines with oxygen and releases energy. • C3H8 (propane) + 5O2 3CO2 + 4H2O

  33. Chemical Change: Evidence • Evidence that a chemical change has occurred might include: • A color change • An odor change • Formation of a precipitate (you mix two liquids and make a solid) • Gas is formed (bubbles) • Changes in physical properties.

  34. Physical and Chemical change • During a chemical change energy can be released in the form of: • Heat • Light

  35. Physical and Chemical change - heat • A chemical reaction that releases energy in the form of heat is called exothermic. • Heat comes OUT • Exo = out • Thermic = heat • It will feel HOT.

  36. Physical and Chemical change - heat • A chemical reaction that absorbs energy in the form of heat is called endothermic. • Heat goes IN • Endo = in • Thermic = heat • It will feel COLD

  37. Quiz time! • Which life cycle is most similar to a chemical change? • Why? Grasshopper = Eggnymphadult Butterfly = egglarvapupaadult

  38. Quiz time! • What type of reaction is most likely occurring here? • How do you know?

  39. Quiz time! • What type of reaction is most likely occurring here? • How do you know?

  40. Quiz time! • What type of reaction is most likely occurring here? • How do you know?

  41. 3/20 Conservation of Mass IQ: You put 100 g of dry ice in a 20g balloon. After a few minutes the balloon blows up from sublimation. How much will the balloon dry ice setup weigh once all the solid dry ice is gone? a. 20g b. 120g c. More than 120g d. Less than 120g.

  42. We’ve talked about changes in matter… • The evaporation of a puddle of water • Rust forming on a metal fence PHYSICAL CHEMICAL

  43. HOWEVER… • No matter is created or destroyed by such changes! • The total amount of matter remains constant.

  44. The Law of Conservation of Matter • During a chemical reaction, matter cannot be created or destroyed. • Even though the matter may change from one form to another, the same number of atoms exists before and after the change takes place!

  45. Since the overall mass of the matter does not change… • The mass of the reactants – the substances there before the reaction occurs – must equal the mass of the product – the substances there after the reaction takes place. Mass of Reactants Mass of Products

  46. An Example of the L.C.M. • Test tube containing lead nitrate is placed upright in a flask that contains potassium iodide. • What are these? • REACTANTS! • They don’t mix!

  47. A stopper is put in place to create a closed system – an environment where matter cannot enter or escape. • The mass of the system is found.

  48. After the mass is found, the system is turned upside down so the lead nitrate can mix with the potassium iodide. • They create lead iodide and potassium nitrate.

  49. Although the matter changed in form, the total mass of the system remains unchanged.

  50. Law of Conservation of Mass • This law states that mass is neither created nor destroyed in a chemical or physical change. • The overall mass of the reactants equals the overall mass of the products. • If water was weighed before boiling it, the mass of collected water vapors will equal the mass of the liquid water.

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