States of Matter

1. States of Matter Physical Science Chapter 3 Physical Science chapter 3

2. States of Matter • All matter has mass and takes up space. • It can exist in 4 states • Solid • Liquid • Gas • Plasma Physical Science chapter 3

3. States of matter • Depends on temperature Physical Science chapter 3

4. Solids • Have definite shape and volume • always the same shape • Cannot be compressed Physical Science chapter 3

5. Kinetic Theory of matter • Tiny particles in constant motion make up all matter. • The faster the particles move, the higher the temperature is • In solids, the particles are held very close together • They can vibrate against each other, but they cannot move out of position. Physical Science chapter 3

6. Liquids • Have a definite volume, but not a definite shape • Won’t spread out to fill container • Can’t force it into smaller container • Take the shape of the container holding them • Cannot be compressed Physical Science chapter 3

7. Kinetic theory • The particles in liquids are very close together • They vibrate against each other, like in solids, but they can also vibrate over and around each other – they can move. Physical Science chapter 3

8. Gases • Have neither a definite shape nor a definite volume • Springy – expand or contract to fill the available space • Pumping air into a basketball • You are compressing the air inside the ball • As it gets fuller, it is harder to pump, because you must compress the air more. Physical Science chapter 3

9. Kinetic Theory • The particles in a gas are free to move around in all directions. • They can separate from each other completely. • They can spread out. Physical Science chapter 3

10. Plasma • Most common form of matter in the universe • Found in stars like the sun • Gaslike mixture of positively and negatively charged particles Physical Science chapter 3

11. Plasma • As matter is heated, the particles move faster. • They collide with greater force. • When they get hot enough, they collide so hard that they break apart into smaller particles. • These smaller particles are electrically charged – positive and negative Physical Science chapter 3

12. Discussion • As water freezes, it expands. • What happens, in terms of particle spacing and arrangement, as water freezes? • What physical property of ice results from this change? Physical Science chapter 3

13. State changes • Changing from one state of matter to another. Physical Science chapter 3

14. Melting • changing from a solid to a liquid Physical Science chapter 3

15. Freezing • changing from a liquid to a solid Physical Science chapter 3

16. Evaporation • When a liquid changes to a gas without boiling. • Example: Water evaporates off your skin when you get out of a swimming pool. Physical Science chapter 3

17. Condensation • When a gas changes to a liquid. • Example: Water vapor from the air condenses on the outside of a cold glass when it is hot and humid. Physical Science chapter 3

18. Sublimation • When a solid changes directly to a gas without being a liquid in between. • Example: Dry ice Physical Science chapter 3

19. Energy and state changes • If you heat ice cubes, you can measure their temperature rising. • When they begin to melt, the temperature stays the same, even though you keep adding heat. • This is because the particles in the ice are absorbing the energy to overcome the forces holding them together. Physical Science chapter 3

20. Water evaporating from your skin • Fast-moving water particles break away and evaporate. • They take energy away from the remaining water. • It is cooler than your skin, so it takes heat away from your skin. • That’s why you get cold. Physical Science chapter 3

21. Conservation of Mass • There is no loss or gain of mass during a chemical change. • Mass is neither created nor destroyed during a chemical change. • Example: burning Physical Science chapter 3

22. Conservation of Energy Physical Science chapter 3

23. Discuss • State whether energy is released or whether energy is required for the following changes of state to take place. • melting • evaporation • sublimation • condensation • If you used dry ice in your holiday punch, would it become watery after an hour? Why or why not? Physical Science chapter 3

24. Pressure • The air exerts a force on everything it touches. • The force is caused by the air particles colliding with their container or surroundings. • Pressure is the amount of force exerted per unit of area. Physical Science chapter 3

25. Pascal • SI unit of pressure • 1 Pa = 1 N/m2 • Very small unit • Like a stick of butter spread out over a square meter • Most pressures are given in kilopascals (kPa) Physical Science chapter 3

26. Buoyant force • The upward force exerted on an object by a fluid (liquid or gas). • The amount of buoyant force determines whether an object will float or sink. Physical Science chapter 3

27. Buoyant force and weight • If the buoyant force is less than the weight, it will sink. • If the buoyant force is equal to the weight, it will float. • If the buoyant force is greater than the weight, it will rise – like a helium-filled balloon. Physical Science chapter 3

28. Archimedes’ principle • The buoyant force on an object is equal to the weight of the fluid displaced by the object. Physical Science chapter 3

29. Wooden block • When you put it in water, it pushes water out of the way until the weight of the water it has displaced equals the block’s weight. Then it floats. Physical Science chapter 3

30. Steel block • When you drop a steel block in water, it pushes water out of the way. • However, even when the block is fully submerged, the weight of the water displaced is less than the weight of the block. • So, it sinks. Physical Science chapter 3

31. Steel ship • If a steel block sinks, why does a steel ship float? • The ship has a greater volume, so it pushes more water out of the way. • The weight of the extra displaced water is equal to the weight of the steel, so the ship floats. Physical Science chapter 3

32. Pascal’s Principle • The pressure applied to a fluid is transmitted unchanged throughout the fluid. • Example: When you squeeze one end of a toothpaste tube, the toothpaste comes out the other end. Physical Science chapter 3

33. Hydraulic lifts • Use Pascal’s principle to lift heavy objects. • Force is applied to a small piston. • The pressure from this force is transferred through the hydraulic fluid to a larger piston. • The force is then used to lift an object. Physical Science chapter 3

34. Example • The pistons of a hydraulic lift have areas of 1.55 m2 and 0.0065 m2. How much force must be applied to the smaller piston if the large piston is to lift a 45,000 N vehicle? Physical Science chapter 3

35. You try • 500 N of force is applied to a piston with an area of 5 cm2. This piston is connected to a piston with an area of 50 cm2. What force does the large piston exert on an object? Physical Science chapter 3

36. Bernoulli’s Principle • As the velocity of a fluid increases, the pressure exerted by the fluid decreases. • This helps airplanes fly. Physical Science chapter 3

37. Airplane wings • Airplane wings are curved. • The air over the top of the wing travels faster, making the pressure above the wing less than the pressure below it. • This lifts the airplane. Physical Science chapter 3

38. Atmospheric pressure • At sea level, the atmosphere exerts a pressure of about 101.3 kPa. • It decreases with increasing altitude. Physical Science chapter 3

39. Discussion • If you release a helium-filled balloon outside, will it break or return to Earth intact? Physical Science chapter 3

40. Sealed container of gas • The pressure depends on how often the particles hit the walls of the container. • If you squeeze the container, making it smaller, the particles hit more often. Physical Science chapter 3

41. Boyle’s Law • If you decrease the volume of a container of gas without changing the temperature, then the pressure of the gas will increase. • If you increase the volume, the pressure will drop. Physical Science chapter 3

42. Example: • A cylinder that has a volume of 0.15 L contains a gas at a pressure of 150 kPa. If a piston compresses the gas at constant temperature to a volume of 0.025 L, what is the new pressure of the gas? Physical Science chapter 3

43. You try: • A flask contains 155 mL of hydrogen at a pressure of 22.5 kPa. Under what pressure would the gas have a volume of 90.0 mL at the same temperature? Physical Science chapter 3

44. Gay-Lussac’s law • If the volume of a gas does not change, then the pressure increases as the temperature increases. • Air pressure in tires increases as they warm up • Pressurized containers of gas explode if they get too hot Physical Science chapter 3

45. Charles’s Law • If the pressure on a gas doesn’t change, then its volume will increase if temperature increases. • If the temperature decreases, so does the volume. Physical Science chapter 3

46. Charles’s Law • In terms of kinetic theory, the gas particles are moving faster as they get hotter. • They hit the walls more often and with more force. • If the walls can move, the container will expand Physical Science chapter 3

47. Absolute zero • Charles calculated the temperature at which a gas would have zero volume. • This is called absolute zero. • -273°C or 0 K • Why won’t a gas ever reach this temperature? Physical Science chapter 3

48. Discussion • Yeast in bread dough reacts with sugar to produce carbon dioxide. • As the bread bakes, the yeast is killed, but the bread keeps rising. • Why? Physical Science chapter 3