1. Chapter Twelve: Properties of Matter Learning Goals  Distinguish chemical properties from physical properties of matter.  Identify differences between crystalline and amorphous solids.  Explain how the arrangement of atoms and molecules in solids determines their properties.

2. Investigation 12A  Key Question: How do solids and liquids differ? Mystery Material

3. Properties of Solids  Different kinds of matter have different characteristics.  Characteristics that can you observe directly are called physical properties.  Physical properties include color, texture, density, brittleness, and state (solid, liquid, or gas). Ex. Iron is solid at room temp.

4. Properties of Solids  A physical change is any change in the size, shape, or phase of matter in which the identity of a substance does not change.  For example, when water is frozen, it changes from a liquid to a solid.

5. Properties of Solids  Properties that can only be observed when one substance changes into a different substance are called chemical properties.  Any change that transforms one substance into a different substance is called a chemical change. Ex. If you leave a nail outside, it rusts. Iron reacts with oxygen to form iron oxide.

6. Properties of Solids The density of a solid material depends on two things: 1.the individual mass of each atom or molecule, 2.how closely the atoms or molecules are packed together. Carbon atoms in diamond are packed very tightly.

7. Properties of Solids  Paraffin wax is also mostly carbon, but its density is only 0.87 g/cm 3.  Paraffin’s carbon atoms are mixed with hydrogen atoms in long molecules that take up more space. The density of paraffin is low compared to diamond.

8. Properties of Solids The atoms or molecules in a solid are arranged in two ways. 1.If the particles are arranged in an orderly, repeating pattern, the solid is crystalline. 2.If the particles are arranged in a random way, the solid is amorphous.

10. Properties of Solids  Examples of crystalline solids include salts, minerals, and metals.

11. Properties of Solids  Metals don’t look like “crystals” because solid metal is made from very tiny crystals fused together in a jumble of different orientations.

12. Properties of Solids  The atoms or molecules in amorphous solids are randomly arranged.  Examples of amorphous solids include rubber, wax, and glass.

13. Mechanical properties  “Strength” describes the ability of a solid object to maintain its shape even when force is applied.

14. Mechanical properties  Tensile strength is a measure of how much stress a material can withstand before breaking.

15. Mechanical properties  Hardness measures a solid’s resistance to scratching. How might you compare the hardness of these two metals?

16. Mechanical properties  Elasticity describes a solid’s ability to be stretched and then return to its original size.  Brittleness is defined as the tendency of a solid to crack or break before stretching very much.

17. Mechanical properties  A ductile material can be bent a relatively large amount without breaking.  The ductility of many metals, like copper, allow then to be drawn into wire.

18. Mechanical properties  Malleability measures a solid’s ability to be pounded into thin sheets.  Aluminum is a highly malleable metal.

19. Mechanical properties  Almost all solid materials expand as the temperature increases.  The increased vibration makes each particle take up a little more space, causing thermal expansion. Sidewalks and bridges have grooves that allow for thermal expansion.

20. Properties of Fluids: Learning Goals  Explain how pressure is created in fluids.  Discuss differences between the density of solids and fluids.  Apply Bernoulli’s principle to explain how energy is conserved in fluids.

21. Properties of Fluids  A fluid is defined as any matter that flows when force is applied.  Liquids like water or silver are kinds of fluid.

22. Pressure  A force applied to a fluid creates pressure.  Pressure acts in all directions, not just the direction of the applied force.

23. Forces in fluids  Forces in fluids are more complicated than forces in solids because fluids can change shape.

24. Units of pressure  The units of pressure are force divided by area.  One psi is one pound per square inch.

25. Units of pressure  The S.I. (Metric) unit of force is the pascal.  One pascal (unit of force) is one newton of force per square meter of area (N/m 2 ).

27. Pressure  If your car tires are inflated to 35 pounds per square inch (35 psi), then a force of 35 pounds acts on every square inch of area inside the tire. What might happen if you over-inflate a tire?

28. Pressure  On the microscopic level, pressure comes from collisions between atoms.  Every surface can experience a force from the constant impact of trillions of atoms.  This force is what we measure as pressure.

29. Pressure  In a car engine high pressure is created by an exploding gasoline-air mixture.

30. Energy conservation and Bernoulli’s Principle  Streamlines are imaginary lines drawn to show the flow of fluid.  Bernoulli’s principle tells us that the energy of any sample of fluid moving along a streamline is constant.

31. Bernoulli’s Principle  Bernoulli’s principle says the three variables of height, pressure, and speed are related by energy conservation.

32. Three Variables and Bernoulli’s Principle  If one variable increases along a streamline, at least one of the other two must decrease.  For example, if speed goes up, pressure goes down.

33. The air foil  One of the most important applications of Bernoulli’s principle is the airfoil shape of wings on a plane.  When a plane is moving, the pressure on the top surface of the wings is lower than the pressure beneath the wings.  The difference in pressure is what creates the lift force that supports the plane in the air.

34. Hydraulics and Pascal’s Principle  Hydraulic lifts and other hydraulic devices use pressure to multiply forces and do work.  The word hydraulic refers to anything that is operated by a fluid under pressure.  Hydraulic devices operate on the basis of Pascal’s principle, named after Blaise Pascal.

35. Hydraulics and Pascal’s Principle  Pascal’s principle states that the pressure applied to an incompressible fluid in a closed container is transmitted equally in all parts of the fluid.  An incompressible fluid does not decrease in volume when pressure is increased.

36. Hydraulics and Pascal’s Principle  A small force exerted over a large distance is traded for a large force over a small distance.

38. Pressure  Pressure is force divided by area.

39. Force  You can calculate the force exerted if you know the pressure and area.

41. Solving Problems  On a hydraulic lift, 5 N of force is applied over an area of 0.125 m 2.  What is the output force if the area of the larger cylinder is 5.0 m 2 ?

42. 1.Looking for:  …output force 2.Given  …input force = 5 N; input area =.125 m 2 ; output area = 5 m 2 3.Relationships:  Pressure = ForceForce = P x A Area Solving Problems

43. 4.Solution  Solve for pressure using input force.  Pressure = 5 N= 40 N/m 2.125m 2  Use Pascal’s law principle and use equivalent pressure to solve for output force.  Force = 40 N x 5 m 2 = m 2 Solving Problems 200 N

44. Viscosity  Viscosity is the property of fluids that causes friction.  Viscosity is determined in large part by the shape and size of the particles in a liquid.

45. Viscosity and temperature  As the temperature of a liquid increases, the viscosity of a liquid decreases.  Increasing the kinetic energy of the substance allows the particles to slide past one another more easily.

46. Please review the following slides. While you did not receive guided notes on these you did cover this material in this unit as well. You are responsible for the following slides.

47. Factors Affecting Fluids: 1. TEMPERATURE and DENSITY  As we have seen, there is a direct relationship between temperature and the density of fluids.  As the temperature of a fluid increases, its density decreases.  Can you think of an example of this relationship in everyday life?

48. Factors Affecting Fluids: TEMPERATURE and DENSITY  As the temperature of a fluid increases, its density decreases.  How can you explain this relationship using the Particle Theory of Matter?  Density columns: Cold water at the bottom, room temperature water in the middle, and hot water at the top.

49. Factors Affecting Fluids: TEMPERATURE and DENSITY  As the temperature of a fluid increases, its density decreases.  How can you explain this relationship using the Particle Theory of Matter?  Density columns: Cold water at the bottom, room temperature water in the middle, and hot water at the top.

50. Factors Affecting Fluids: TEMPERATURE AND VOLUME  There is a direct relationship between temperature and the amount of volume taken up by a fluid.  As the temperature of a fluid increases, the amount of volume it takes up increases. This is particularly true for gases.  Can you think of an example of this relationship in everyday life?

51. Factors Affecting Fluids: TEMPERATURE AND VOLUME  As the temperature of a fluid increases, the amount of volume it takes up increases. This is particularly true for gases.  Can you think of an example of this relationship in everyday life?  A basketball that is left outside the sun will be more pumped up than a basketball that is left outside in the cold. This is because the sun warms up the particles inside the ball, weakening the bonds between them, and allowing them to move faster, and spread farther apart, taking up more volume.

52. Factors Affecting Fluids: TEMPERATURE AND VOLUME  As the temperature of a fluid increases, the amount of volume it takes up increases.

53. Factors Affecting Fluids: TEMPERATURE AND PRESSURE  There is a direct relationship between temperature and the pressure inside a fluid.  As the temperature of a fluid increases, the pressure of a fluid in a closed space increases.  Can you think of an example of this relationship in everyday life?

54. Factors Affecting Fluids: TEMPERATURE AND PRESSURE  As the temperature of a fluid increases, the pressure of a fluid in a closed space increases.  Can you think of an example of this relationship in everyday life?  When you try to fit a gas into a smaller space (volume), the pressure inside increases. For example, when you squeeze a balloon that is filled with air, the pressure builds up inside to the point that it might burst if you decrease the volume inside too much.

55. Factors Affecting Fluids: TEMPERATURE AND VISCOSITY  As we have seen, there is a direct relationship between temperature and the viscosity of fluids.  As the temperature of a fluid increases, its viscosity decreases.  Can you think of an example of this relationship in everyday life?

56. Factors Affecting Fluids: TEMPERATURE AND VISCOSITY  As the temperature of a fluid increases, its viscosity decreases.  How can you explain this relationship using the Particle Theory of Matter?  A liquid at a warmer temperature flows more easily/quickly than a liquid at a colder temperature. For example, if you can’t get honey to flow out of its container, you can warm it up in the microwave for a few seconds until it flows out.

57. Factors Affecting Fluids: TEMPERATURE and Particle Bond Strength  There is a direct relationship between temperature and the strength of bonds between particles in fluids.  As the temperature of a fluid increases, its particle bond strength decreases.  Can you think of an example of this relationship in everyday life?

58. Factors Affecting Fluids: TEMPERATURE and Particle Bond Strength  As the temperature of a fluid increases, its particle bond strength decreases.  Can you think of an example of this relationship in everyday life?  Using warm water works better when you try to remove a stain or dirt from an object because the warmth loosens the bonds between the particles, allowing them to separate better.

59. How Temperature Affects Fluids  Fill out the table below to show the relationship between temperature, compression, and fluid properties. BOND STRENGTH VOLUME DENSITY VISCOSITYPRESSURE As Temperature INCREASES… As Temperature DECREASES..

60. Factors Affecting Fluids PHET SIMULATION of how temperature and compression affect the density, volume, and pressure of fluids. http://phet.colorado.edu/en/simulations /category/physics/work-energy-and- power http://phet.colorado.edu/en/simulations /category/physics/work-energy-and- power

61. WATER: An Exception  Water is an exception to many fluid dynamic relationships.  Water has a greater volume at a high temperature (it goes from liquid to gas form), but when water freezes at low temperatures, its volume ALSO increases (like when you freeze a plastic bottle of water and the plastic breaks).  The density of water also doesn’t follow the typical fluids rule. Frozen water (ice) is less dense than liquid water, so ice floats in water. Could you imagine what the world would be like if water did follow the typical fluids rule that frozen fluids are more dense than liquid fluids of the same kind? What would the world look like?