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Phase Changes. Review: 4 Phases of Matter Solid Solid Liquid Liquid Gas Gas Plasma Plasma.

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Presentation on theme: "Phase Changes. Review: 4 Phases of Matter Solid Solid Liquid Liquid Gas Gas Plasma Plasma."— Presentation transcript:

1 Phase Changes

2 Review: 4 Phases of Matter Solid Solid Liquid Liquid Gas Gas Plasma Plasma

3 What is a Phase Change? Phase ChangePhase Change It is a change from one state of matter It is a change from one state of matter (solid, liquid, gas) to another. Phase changes are physical changes because: Phase changes are physical changes because: - It only affects physical appearance, not chemical make-up. not chemical make-up. - Reversible

4 What happens during a phase change? During a phase change, heat energy is either absorbed or released. During a phase change, heat energy is either absorbed or released.

5 What is Exothermic change? Heat energy is released as molecules slow down and move closer together. Heat energy is released as molecules slow down and move closer together. Example: Gas to Liquid Example: Gas to Liquid

6 What is Endothermic change? Heat energy is absorbed as molecules speed up and expand. Heat energy is absorbed as molecules speed up and expand. Example: From solid to liquid Example: From solid to liquid

7 Types of Phase Changes

8 What is Melting? Phase change from a solid to a liquid Phase change from a solid to a liquid Molecules speed up, move farther apart, and absorb heat energy Molecules speed up, move farther apart, and absorb heat energy

9 What is Freezing? Phase Change from a liquid to a solid Molecules slow down, move closer together and release heat energy.

10 Vaporization (Boiling) Phase change from a liquid to gas. It occurs at the boiling point of matter. Phase change from a liquid to gas. It occurs at the boiling point of matter. Molecules speed up, move farther apart, and absorb heat energy. Molecules speed up, move farther apart, and absorb heat energy.

11 What is Evaporation? Phase change from a liquid to a gas Phase change from a liquid to a gas Molecules speed up, move farther apart, and absorb heat energy. Molecules speed up, move farther apart, and absorb heat energy.

12 What is Condensation? Phase change from a gas to a liquid. Phase change from a gas to a liquid. Molecule slow down, move closer together and release heat energy. Molecule slow down, move closer together and release heat energy.

13 Sublimation is? Phase change from a solid directly to a gas. Phase change from a solid directly to a gas. Liquid state doesn’t happen..!!! Liquid state doesn’t happen..!!! Molecules speed up, move farther apart, and absorb heat energy. Molecules speed up, move farther apart, and absorb heat energy. Example: Example: As dry ice (frozen carbon dioxide gas) As dry ice (frozen carbon dioxide gas) gets warmer, it turns gets warmer, it turns into carbon dioxide gas into carbon dioxide gas

14 Deposition is? Phase change from a gas to a solid. Phase change from a gas to a solid. Again.. Liquid state doesn’t happen..!!! Again.. Liquid state doesn’t happen..!!! Molecules slow down, move closer together and release heat energy. Molecules slow down, move closer together and release heat energy.

15 Melting & Boiling Points What is Melting Point: The temperature at which a solid changes into a liquid. What is Boiling Point: The temperature at which a liquid changes into a gas. What is a Freezing point? Point at which liquid becomes solid.

16 Summary

17 Summary When Heat energy is released it is called? Exothermic change Think of the prefix Exo as Exit

18 Summary When Heat energy is absorbed it is called? When Heat energy is absorbed it is called? Endothermic change Endothermic change The prefix endo means in The prefix endo means in

19 Graphing a Phase Change – Why is there no change in temperature when changing solid to liquid and liquid to gas? when changing solid to liquid and liquid to gas? – Because the heat energy is used get the molecules to move faster and faster, until ice changes to liquid to move faster and faster, until ice changes to liquid and eventually liquid will change to gas and eventually liquid will change to gas

20 Graphing a Phase Change – Define melting point * Melting Point happens when all the molecules * Melting Point happens when all the molecules have so much energy that they now change have so much energy that they now change into the liquid state of matter into the liquid state of matter

21 Graphing a Phase Change What is the melting point and boiling point of water? What is the melting point and boiling point of water? Pure Water melts Pure Water melts at 0 C or 32 F at 0 C or 32 F Pure Water boils Pure Water boils at 100 C or 212 F at 100 C or 212 F o o o o

22 Graphing a Phase Change  At what temperature does water freeze and become a solid? Pure Water freezes at Pure Water freezes at 0 C or 32 F 0 C or 32 F o o

23 Directions Directions Take out your science notebook or your phone notes and write down the Take out your science notebook or your phone notes and write down the following questions and answers following questions and answers

24 1. Name six common phase changes. Melting, freezing, vaporization, condensation, sublimation, and deposition. Melting, freezing, vaporization, condensation, sublimation, and deposition. 2. What happens to the temperature of a substance during a phase change? The temperature of a substance does not change during a phase change. The temperature of a substance does not change during a phase change. 3. What is the difference between evaporation and boiling? Evaporation takes place at the surface of a liquid and occurs at temperatures below the boiling point. Boiling point of pure water is 100 degrees Celcius Evaporation takes place at the surface of a liquid and occurs at temperatures below the boiling point. Boiling point of pure water is 100 degrees Celcius

25 4. How does the energy of a system change during a phase change? Energy is either released or absorbed during a phase change. 5. What happens to the arrangement of water molecules as water melts and freezes? The arrangement of molecules becomes less orderly as water melts and more orderly as water freezes.

26 6. What is the difference between Endothermic and Exothermic change? During endothermic change energy is absorbed from the surroundings, such as hot stove During exothermic change energy is released into the surroundings 7. What are the freezing and boiling points of pure water Freezing point is 0 degree Celcius and 32 degrees Fahrenheit Boiling point is 100 degrees Celsius and 212 degrees Fahrenheit

27 Homework tonight…… Complete: Complete: “Molecules on the move worksheet” “Molecules on the move worksheet” Write the correct Phase of matter and also include whether it was an Exothermic or Endothermic change Write the correct Phase of matter and also include whether it was an Exothermic or Endothermic change HW is due tomorrow..!! Oh yes..! HW is due tomorrow..!! Oh yes..!


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