Unit 5 Study Guide Answers

Unit 5 Study Guide: Phases Changes Answers • Phases of Matter • Phases of Matter Worksheet 1. What are the three parts of the kinetic theory? • All matter is composed of small particles (molecules, atoms, and ions) • The particles are in constant random motion • The particles are colliding with each other and the wall of their container 2. T/F Not all particles are in constant random motion. False 3. Why are solids closely packed together? Because there is an attractive force holding them together 4. Are the particles of a solid bonded together? No they are not chemically bonded 5. T/F The particles of a solid are constantly vibrating. True 6. In which phase of matter can the particles not slip past one another? Solids 7. What type of phase cannot be poured and has a definite shape? Solid 8. What phase has a definite shape and a definite volume? Solid 9. T/F The particles of liquids are not in contact with each other. False 10. T/F Bonds hold the particles of solids together but not the particles of liquids. False bonds do not hold any particles together it is attractive forces 11. Why can liquid particles slip past one another? Because they are moving fast enough to partially overcome the attractive force of the surrounding particles and thus slip past each other. 12. Why can liquids be poured? Because they can slip past one another 13. What phase has no definite shape but has a definite volume? Liquid 14. In what phase are the particles close together but flow freely? Liquid

15. Why are the particles of gas not in contact with each other? Because they are moving fast enough to completely overcome the attractive force between or among the particles 16. Which phase has no definite shape and no definite volume? Gas 17. How would you best describe the movement of gas particles? They are moving randomly in straight lines. They bump into each other and the walls of the container and bounce off 18. What phase can expand to fill available space? Gas 19. Why can gases spread into different shapes? Gas. Liquid is limited by its volume and gas is not because it does not have a definite volume. 20. What is the most common phase of matter in the universe? Plasma 21. How would you best describe how something is converted into a plasma? At very high temperatures particles are moving extremely fast. When the particles collide at such high speeds some of the electrons are stripped. 22. What phase exists naturally only in stars? Plasma 23. What phase occurs mostly as crystals? Solid • Phase changes 24. What common measurement is used to describe the average kinetic energy of the particles in a substance? Temperature 25. As average kinetic energy increases, what happens to the speed of the particles? As you increase average kinetic energy, the speed increases 26. What type of energy is associated with motion? Kinetic energy is associated with motion 27. What is happening at the freezing/melting point? Particles are changing from a liquid to a solid. The temperature remains constant. 28. Why does a solid melt? When heat is added the attractions between the particles are weakened 29. How do you get attractions to form, causing a liquid to freeze? By removing heat.

30. What is happening at the boiling point? A liquid changes to a gas. The temperature does not change. 31. When something boils, what is being released in the bubbles? Vapor or gas 32. When you add energy to a substance, the energy of the particles increases. What is the evidence for this? The temperature increases or there is a phase change 33. When you add heat to a solid, the temperature increases. What happens to the temperature when you add heat at the melting/freezing point? It remains the same 34. When you add heat to a liquid at the boiling point the temperature does not change. What is the extra heat used for? To break the attractive forces 35. For the temperature vs. Time graph be able to a. Describe what is happening to the slope before the phase change occurs It is positive b. Describe what is happening to the slope when the phase change is occurring It is flat or zero. Phase changes are flat! c. Describe what is happening to the slope after the phase change has occurred It is positive d. Describe what is happening to the average kinetic energy before the phase change occurs It is increasing e. Describe what is happening to the average kinetic energy while the phase change occurs It remains the same f. Describe what is happening to the average kinetic energy after the phase change occurs It is increasing 36. Why can liquids evaporate at any temperature? Because some of the molecules at the surface are moving fast enough to escape the attraction of the other molecules 37. What is sublimation? When a substance goes from a solid to a gas

38. What happens to the kinetic energy during 2? It stays the same 39. What happens to the kinetic energy during 3? It increases 40. What number indicates where the substance is a solid being heated up? #1 41. What number indicates where the substance is a liquid being heated up? #3

going from a solid to a liquid? #2 48. What number indicates where something is going from a gas to a liquid? #4 49. At what number would you find the fastest moving particles? #5 50. At what number would you find the slowest moving particles? #1

42. What number indicates where the substance is a gas being heated up? #5

51. What is the independent variable? Time

43. What number indicates melting point? #2

52. What is the dependent variable? Temperature

44. What number indicates freezing point? #2

53. At what temperature does the substance melt? 0 oC

45. What number indicates boiling point? #4 46. What number indicates where something is crystallizing? #2 47. What number indicates where something is

54. At what temperature does the substance boil? 100 oC 55. At what temperature does the substance freeze? 0 oC