As ice melts in a glass of ice water do you think the temperature of the drink changes Why or why not?

Transcription

1 As ice melts in a glass of ice water do you think the temperature of the drink changes Why or why not?

2 Phase Change Phase Change- Is the reversible physical change that occurs when a substance changes from one state of matter to another.

3 Are these phase changes?

4 Are these phase changes?

5 States of matter

6 Six physical- phase changes Melting is the phase change from a solid to a liquid Solidification/freezing- is the phase change from a liquid to a solid Condensation is the phase change from a gas to a liquid Vaporization is the phase change from a liquid to gas Deposition is the phase change from a gas to a solid Sublimation is the phase change from a solid to a gas

7 Draw this diagram in your notes

8 Share with you neighbor the six different types of phase change Make sure to put each definition in your own words

9 Quick Quiz: List The six common phase changes and what you know about each

10 Temperature and phase change Temperature is A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of unit of degrees designated on a standard scale A measure of warmth or coldness of an object or substance with reference to some standard value

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12 Based on the two definitions of temperature What are we measuring when we measure a substance s temperature? What does kinetic energy have to do with temperature? What is Kinetic energy?

13 The Kinetic Theory of Matter

14 The Theory 1. Matter is composed of particles that are in constant motion

15 Why do we have this Theory? 1. Helps us predict 1. Heat transfer 2. Pressure 3. Temperature 4. Properties of matter

16 Motion 1. These particles have spaces in between them 1. They move around in these spaces

17 Gases 1. In gases, the spaces are far apart

18 Liquids 1. In liquids, the spaces are smaller 1. Now there is a fixed volume

19 Solids 1. Even in solids, the particles are moving 1. Now there is a fixed shape, too

20 Effects of Energy 1. If the temperature is raised, the particles move faster 1. And visa versa

21 Basically 1. The higher the temperature, the faster the particles move Solids- Liquids-

22 How these Theories Connect 1. The more thermal energy, the faster the particles move

23 Conclusion 1. The Kinetic theory of Matter 1. Particles in matter are always moving 2. The higher the temperature, the faster they move

24 Phase change is about energy Energy is either absorbed or released during a phase change. The kinetic energy of the molecules is being transferred.

25 Quick Quiz 1. Define temperature 2. Define kinetic energy 3. Describe what happens to the temperature of water as it goes through a change of state. 4. Describe how a phase change is about energy being transferred.

26 Melting Solid to liquid Endothermic change the system absorbs energy from its surroundings. Energy is transferred to the ice and the ice melts.

27 Endothermic Endo means within Thermic caused by heat Endothermic the heat within thermal underwear keeps the heat within Say together: Endothermic is a heat taker. Define endothermic in your own words. Draw a picture in your notes to represent endothermic.

28 Which are exothermic changes? In your notes draw this diagram with only the endothermic changes. Remember they are the changes that need energy.

29 With your partner Share your diagram Compare what you identified as endothermic changes. Decide what is correct and fix your diagram if needed.

30 Heat of Fusion The energy required to change a gram of a substance from the solid to the liquid state without changing its temperature is commonly called it's "heat of fusion".

31 Exothermic change Freezing is exothermic change As water freezes it releases energy. Exomeans outside Thermic heat Exothermic outside heat Say: EXO is a heat giver.

32 Which are exothermic changes? In your notes draw this diagram with only the endothermic changes. Remember they are the changes that need energy.

33 With your partner Share your diagram Compare what you identified as endothermic changes. Decide what is correct and fix your diagram if needed.

34 Vaporization and Condensation Liquid to a gas is vaporization. It is an endothermic process. Does that mean it is an energy taker or energy giver? It is an energy taker, a gram of water needs 2261 joules of energy when it vaporizes. The energy absorbed is called the heat of vaporization.

35 Heat of vaporization The energy required to change a gram of a liquid into the gaseous state at the boiling point is called the "heat of vaporization".

36 In your notes Write a definition of Heat of Vaporization in your own words. Draw a picture of Heat of Vaporization.

37 Two vaporization processes Evaporation takes place at the surface of a liquid and occurs at temperatures below the boiling point. Boiling occurs when there is enough heat applied for both the temperature and vapor pressure to increase to the point that the vapor pressure becomes equal to the atmospheric pressure.

38 Describe when water is boiling What is happening to the water molecules? What happens to the temperature of the water once it hits the boiling point? Why do bubbles form and float up?

39 Condensation Gas or vapor to a liquid Is it an endothermic or exothermic process? It is exothermic energy is released? What causes car windows to fog up?

40 Quick Quiz 1. What are the two forms of vaporization? 2. How are they different? 3. Is vaporization a energy giver or taker? 4. Does that make the process endothermic or exothermic?

41 Sublimation Sublimation is the phase change from a solid to a gas. Dry ice is solid carbon dioxide and changes from a solid to a gas at room temperature without going through a liquid stage. Do you believe sublimation to be an energy giver or an energy taker? Sublimation is endothermic an energy taker.

42 How can the mass of a pile of snow decrease on a sunny day when the temperature never goes above freezing?

43 Deposition Deposition is the change of state from a gas to a solid. Do you believe it is an energy giver or energy taker? It is exothermic an energy taker. Deposition caused frost to form on windows. What happens to the kinetic energy of the water vapor as it hits the cold window?

44 On a sheet of paper 1. Explain six common phase changes. 2. Explain energy in a phase change. 3. Describe the arrangement of water molecules during melting and freezing. 4. Explain the differences between evaporation and boiling.