States of Matter

1. States of Matter

2. Materials can be classified as either solids, liquids, or gases based on whether their shapes and volumes are definite or variable.

3. What does “Definite” mean? • That it (the shape or volume) doesn’t change as you change the container. • It doesn’t mean that the shape or volume can never change.

4. 3 Main Types of Matter • Solid- matter with a definite shape and definite volume • Liquid- matter with a definite volume, but with a variable shape • Gas- matter that has a variable volume and a variable shape

5. Other Types of Matter… • Plasma- a state of matter that exists at extremely high temperature state of matter, accounts for 99% of all matter in universe • Bose-Einstein Condensate (BEC) – a state of matter that exists at extremely low temperatures

6. Solids, Liquids and Gases

7. Kinetic Molecular Theory • A theory of matter that accounts for the behavior of the atoms and molecules that make up matter. It is based on the idea that particles of matter are always in motion. • KMT also states that there are forces of attraction among the particles in all matter. • The KMT explains the properties of solids, liquids, and gases in terms of the energy of the particles and the forces that act between them.

8. Kinetic energy is… • The energy an object has due to its motion. • More motion means more kinetic energy.

9. Explaining the Behavior of Solids with the KMT • Solid particles have the least kinetic energy of all the states of matter • Strong attractive forces between the molecules prevent movement from place to place, but the particles in a solid still vibrate in place

10. Explaining the Behavior of Solids with the KMT • Particles are packed together as tightly as possible in a neat and organized arrangement • Hard to compress because there is no real “empty” space between the particles

11. Example… • A polite audience in a movie theater.

12. Explaining the Behavior of a Liquid with the KMT • Particles have more kinetic energy than solids, but less than gases. • Liquids take the shape of their containers because particles in a liquid can flow to new locations • The volume of a liquid is constant because forces of attraction keep the particles close together.

13. Explaining the Behavior of a Liquid with the KMT • The forces of attraction are less than those in solids and so this allows the particles to move from one location to another. • Particles moving rapidly in all directions with frequent collisions • Not easily compressed due to lack of “empty” space between molecules

14. Example… • People walking in a crowded hallway

15. Explaining the Behavior of a Gas with the KMT • Gas particles have most kinetic energy of the 3 common states of matter • Particles in a gas are in constant random motion, they travel in straight lines until they collide with something else. • Particles move rapidly in all directions, colliding frequently with one another, though not as often as in liquids

16. Explaining the Behavior of a Gas with the KMT • The motion of one gas particle is unaffected by the motion of other particles unless they collide. • Forces of attraction among particles in a gas can be ignored under ordinary conditions. • Particles are readily compressed because of the “empty” space between the particles

17. Gas vs. Vapor • The terms “gas” and “vapor” are not interchangeable!!! • Vapor: def: the gaseous state of a substance that is generally a liquid or solid at room temperature.

18. Volume • Solids: • Definite volume • Liquids: • Definite Volume • Gases: • Indefinite Volume; expands to fill container

19. Shape • Solids: • Definite shape • Liquids: • Indefinite Shape; takes the shape of the container • Gases: • Indefinite shape; takes the shape of the container

20. Amount of kinetic energy of the particles • Solids: • Least energy • Liquids: • More energy than a solid but less than a gas • Gases: • Most energy

21. Particle movement and arrangement • Solids: • Vibrate about a fixed position • Close together and very organized • Not a lot of empty space between the molecules • Liquids: • Move quickly and randomly around one another • Loosely and randomly organized • A little more empty space than solids had • Gases: • Move extremely fast and are all over the place • Very far apart with no set organization • Tons of empty space between molecules

22. Attractive Forces Between Molecules • Solids: • Strongest forces of attraction between the molecules • Liquids: • In between • Gases: • Weakest forces of attraction between the molecules; explains why the molecules are free to move wherever they want

23. On a sheet of paper… • In as much detail as you can, describe on a molecular level what is happening to an ice cube that is dropped into a cup of hot tea. • Think about motion, energy, arrangement, and attractive forces… Put this paper to the side… you’ll add work to it later and then turn it in.

24. Phase Change… what is it? • A physical change in which a substance changes from one state of matter to another. • It is reversible.

25. What does the temperature of a substance do during a phase change? • The temperature of a substance does NOT change during a phase change.

26. How is energy involved in a phase change? • Energy is either absorbed or released during a phase change. • Endothermic change: energy is absorbed (energy goes “en”to the substance) • Exothermic change: energy is released (energy “ex”it’s the substance)

27. Melting and Freezing • The arrangement of molecules in water becomes less orderly as water melts and more orderly as water freezes. • http://www.visionlearning.com/library/module_viewer.php?mid=120

28. Melting • Phase change of a solid to a liquid • Does a solid gain or lose energy in order to become a liquid? • Gains… • therefore melting is an endothermic change. • Melting occurs when some of the molecules gain enough energy to overcome the forces of attraction that are holding them in one spot enough that they can begin to move around.

29. Freezing • Phase change of a liquid to a solid • Does a liquid gain or lose energy in order to become a solid? • loses… • therefore freezing is an exothermic change. • Freezing occurs when the molecules begin to move slow enough that the forces of attraction are felt so strongly that the liquid molecules become held in one spot and take on an orderly arrangement.

30. Vaporization • Phase change in which a liquid changes to a gas. • Does a liquid gain or lose energy in order to become a gas? • Gains… • Therefore vaporization is an endothermic change. • Two types of vaporization • Evaporation • Boiling

31. What’s the difference between evaporation and boiling? • Evaporation • Temperature of the liquid has to be below the boiling point of that liquid. • Takes place at the surface of the liquid as molecules near the surface move fast enough to escape the liquid and become a vapor. • The bigger the surface area the faster the evaporation rate.

32. Boiling • Temperature of liquid has to be at the boiling point of that liquid. • Occurs below the surface of the liquid as molecules gain enough kinetic energy (due to being heated) that they enter the gaseous phase and thereby form bubbles in the liquid that float to the top and escape.

33. Condensation • Phase change of a gas to a liquid • Does a gas gain or lose energy in order to become a liquid? • loses… • therefore condensation is an exothermic change. • Condensation occurs when the molecules of a gas begin to move slow enough that the forces of attraction are felt strongly enough that the gas molecules become attracted to one another and form a liquid.

34. Sublimation and Deposition • Sublimation • Phase change in which a solid turns to a gas without passing through the liquid phase. • Endothermic • Deposition • Phase change in which a gas turns to a solid without passing through the liquid phase. • Exothermic.

35. On a sheet of paper… • In as much detail as you can, describe on a molecular level what is happening to an ice cube that is dropped into a cup of hot tea. • Think about motion, energy, arrangement, and attractive forces… • Add to your earlier answer based on what you’ve just learned. Then do questions 1-8 on page 91 in your book.

36. Phase Changes Anytime matter changes to a higher energy state, energy must be added. Anytime matter changes to a lower energy state, energy is released.

39. Heating Curve • What is this substance’s melting point? ___________ • What is this substance’s freezing point? ____________ • What is this substance’s boiling point? _____________ • Could this substance be water? _____________

40. Fill in the two missing temperatures. • What is the temperature of ice water? • If you boil water for 15 minutes, what will happen to the temperature of the water?

41. Remember… all graphs should have… • Appropriate title • Labeled x and y axis (tell what is being measured as well as the unit of that measurement) • An even and consistent scale • the graph should take up at least ½ the available graph area • For this lab, the time goes on the x-axis, the temperature goes on the y-axis.

42. How Distillation Works:

44. Equilibrium in a Closed System

45. Equilibrium in a Closed System Gas and Liquid Gas and Solid Note that the rate of evaporation of the liquid is equal to the rate of condensation of the gas. Note that the rate of evaporation of the solid is equal to the rate of condensation of the gas.

46. Effect of Temp on Equilibrium Liquid and Gas Liquid and Gas Low TemperatureHigh Temperature Note the large number of particles in the gas. Note the small number of particles in the gas.

47. Triple Point: the temperature and pressure at which the solid, liquid, and vapor of the substance can coexist at equilibrium

48. Phase Diagrams • Definition: a graph of pressure versus temperature that shows the conditions under which the phases of a substance exist

49. Critical Point: indicates the critical temp and critical pressure of a substance • Critical Temperature: the temp above which the substance cannot exist in the liquid state • Critical Pressure: the lowest pressure at which the substance can exist as a liquid at the critical temperature

50. Phase Diagram of Water • Describe all the phase changes a sample of solid water would undergo when heated to its critical temp at a pressure of 1.00 atm. • Describe all the phase changes a sample of water vapor would undergo when cooled to 5°C at a pressure of 1.00 atm. • At approximately what pressure will water be a vapor at 0°C? • Within what range of pressures will water be a liquid at temps above its normal BP?