Notes – Changes in States of Matter

1. Notes – Changes in States of Matter Chapter 6, Lesson 2

2. Temperature, Thermal Energy, & Heat • Changes in energy can cause matter to change from one state to another. • A state change happens because of the change in motion of particles in an object. Matter Changing State

3. Temperature, Thermal Energy, & Heat • Even when an object is not moving, the particles in the object are moving. • The particles have kinetic energy, which is energy of moving things. The gas particles inside the balloon have energy because they are moving.

4. Temperature, Thermal Energy, & Heat

5. lower temperature higher temperature Temperature, Thermal Energy, & Heat • Temperature is a measure of the average kinetic energy of the particles in a material. • Particles in matter move faster as the temperature increases.

6. Temperature, Thermal Energy, & Heat • A thermometer is used to measure temperature. • Particles in the thermometer’s gauge increase their speed when heated and start moving farther apart, causing the liquid in the thermometer to rise.

7. Temperature, Thermal Energy, & Heat • Particles in a substance have potential energy. • Potential energy decreases as particles move closer together. • Potential energy increases as particles move farther apart.

8. Temperature, Thermal Energy, & Heat

9. Temperature, Thermal Energy, & Heat • The total energy of the particles of a substance is its thermal energy. • Includes kinetic energy and potential energy of a substance’s particles • A substance’s liquid state has more thermal energy than its solid state • A substance’s gas state has more thermal energy than its liquid or solid state.

10. Temperature, Thermal Energy, & Heat • Heating adds thermal energy. • Cooling removes thermal energy.

11. Temperature, Thermal Energy, & Heat • When kinetic energy increases, the temperature of a substance increases. • When potential energy increases, the substance changes state.

12. Melting • solid → liquid • Thermal energy is absorbed. • Potential energy increases. • Melting point is the temperature at which a material changes from solid to liquid.

13. Melting • Thermal energy is added to a solid, & the temperature increases until the melting point is reached. • The substance will not increase temperature until it has completely melted.

14. Melting • The average kinetic energy does not change, only the potential energy changes. • The attractive forces become weaker as particles increase speed and move farther apart.

15. Melting

16. Freezing • liquid → solid • Thermal energy is released. • Potential energy decreases. • Freezing point is the temperature at which a liquid changes to a solid.

17. Freezing

18. Vaporization • liquid → gas • Thermal energy is absorbed. • Particles become too spread out and the attractive forces are too weak to keep the particles close together. • Vaporization can occur both at the surface and inside the liquid.

19. Vaporization: Boiling • Vaporization that occurs inside the liquid. • Boiling point refers to the temperature that boiling occurs in a substance.

20. Vaporization: Boiling

21. Vaporization: Boiling • The boiling point depends on the pressure exerted on the liquid. • Bubbles in the liquid must form for boiling to occur. • As air pressure increases, it becomes harder for the bubbles to form. • The boiling point increases as air pressure increases.

22. Vaporization: Evaporation • Evaporation is vaporization that occurs at the surface of a liquid. • Evaporation occurs both at the boiling point and temperatures below the boiling point.

23. Vaporization: Evaporation • The liquid gains thermal energy, and molecules on the surface gradually escape into the atmosphere • (i.e.) water cycle, a puddle after rain, sweating to cool you down

24. Condensation • gas → liquid • Thermal energy is released. • The gas particles slow down and move closer together until the attractive forces hold them together and a liquid forms.

25. Condensation

26. Sublimation • solid → gas • Thermal energy is absorbed. • Bypasses liquid state completely. • Dry ice (solid carbon dioxide) changes from a solid to a gas.

27. Deposition • gas → solid • Thermal energy is released. • Bypasses liquid state completely. • Water vapor changes directly to ice as frost on leaves.

28. Adding Thermal Energy • The temperature of ice increases until the melting point is reached. • The temperature stays constant as the ice melts.

29. Adding Thermal Energy • After the ice has melted, the temperature increases until the boiling point is reached. • The temperature stops increasing until all the water has changed to water vapor.

30. Adding Thermal Energy • Adding more thermal energy causes the temperature of the water vapor to increase.

31. Removing Thermal Energy • Water vapor changes back into ice by removing thermal energy.

32. Changes in Energy Among States of Matter

33. 6.2 Changes in States of Matter 1. The point at which a liquid changes to a gas is called ____. A melting point B freezing point C condensation point D boiling point

34. 6.2 Changes in States of Matter 2. A liquid can change to a gas through ____. A evaporation B freezing C melting D sublimation

35. 6.2 Changes in States of Matter 3. Thermal energy must be ____ when a liquid changes to a ____. A lost; gas B gained; solid C lost; solid D increased; solid

36. 4. Sublimation occurs when a solid changes into a ____. A liquid B gas C plasma D steam

37. 5. As air pressure ____, the ____ of a liquid increases. A decreases; boiling point B decreases; freezing point C increases; freezing point D increases; boiling point

38. SCI 3.e 6. Adding thermal energy can ____ or ____. A lower temperature; change the state of matter B increase temperature; lower temperature C increase temperature; change the state of matter D remove kinetic energy; change the state of matter

39. SCI 3.e 7. One glass of water has a temperature of 30°C and another glass of water a temperature of 40°C. Which is true? AThe glass of water at 30°C has lower average kinetic energy. BThe glass of water at 40°C has lower average kinetic energy. CThe two glasses have equal average kinetic energy. D none of the above