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Phases & Behavior of Matter Chs 13, 17,

1. Phases & Behavior of Matter Chs 13, 17,. 2. Phases and Behavior of Matter Goals. Understand the effects motion of atoms and molecules in chemical and physical processes. b. Compare and contrast atomic/molecular motion in solids, liquids, gases, and plasmas.

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Phases & Behavior of Matter Chs 13, 17,

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  1. 1 Phases & Behavior of MatterChs 13, 17,

  2. 2 Phases and Behavior of Matter Goals • Understand the effects motion of atoms and molecules in chemical and physical processes. b. Compare and contrast atomic/molecular motion in solids, liquids, gases, and plasmas. c. Collect data and calculate the amount of heat given off or taken in by chemical or physical processes. d. Analyzing (both conceptually and quantitatively) flow of energy during change of state (phase). e. Apply concepts of the mole and Avogadro’s number to conceptualize and calculate molar volumes of gases. Solid Liquid Gas

  3. 3 Clip Kinetic Theory of Matter • All matter is composed of small particles (atoms). • These particles are in constant motion. • These particles are colliding with each other and the walls of their container.

  4. 4 Kinetic Energy • Kinetic Energy is the energy of motion. • Temperature is the measurement of the KE in an object. • So, the more KE the higher the temp. • As the particles in an object gain KE, the temperature goes up.

  5. 5 Clip Amorphous Solids Solids • Particles are closely packed together. • Most are geometric. (called Crystals) • There are bonds between atoms/mol. • Rigid shapes. • Definite shape. • Definite volume. • Particles are closely packed together. • Most are geometric. (called Crystals)

  6. Crystalline solids are arranged in fixed geometric patterns or lattices. Amorphous Solids 6 • Lack highly ordered internal arrangement • Melt over a temperature range • Glass • Super-cooled liquid • Plastics • Some scientist classify them as “thick liquids” “without form” • Amorphous solids are solids with random unoriented molecules

  7. 7 Clip Liquids • Particles in a liquid have more KE than particles in a solid. • Liquid particles have enough KE to overcome the forces that hold them together. • The particles can now move past one another. (flow) • Definite volume • No Definite shape. Viscosity • Resistance to flow Viscosity

  8. 8 Clip Gases • Gas particles have more KE than liquid particles. • They have enough energy to break all bonds and escape the liquid state. • Particles are far apart- no attractice forces between them

  9. 9 Gases • Motion of the molecules is random. • During collisions between particles, KE is transferred without loss of total energy. • No definite Shape • No definite Volume.

  10. 10 Gases are compressible

  11. 11 Clip Plasma • Most common state of matter in the universe • Extremely high temperatures. • Contains positively and negatively charged particles

  12. 12 Terrestrial plasmas • Lightning • The ionosphere • The polar aurorae • Artificially produced plasmas • Those found in plasma displays, including TVs • Inside fluorescent lamps (low energy lighting), neon signs • The electric arc in an arc lamp, an arc welder or plasma torch • Plasma ball (sometimes called a plasma sphere or plasma globe)

  13. 13 • Force produced by high energy collisions strips electrons from atoms. • Sun, lighting bolts, neon and fluorescent tubes, auroras. ReviewClip

  14. 14 Gasses exert pressure on the walls of their containers and objects around them. • Pressure- measure in Pa • Atmospheric pressure- collision of atoms and molecules in the air with object. -Standard pressure (atm) at 25˚C • Barometer- measure atm pressure • Conversions- Units of pressure • (Q) What is 450kPA in mmHg and atm? • 4.4 atm • 3.4 x 103 mm Hg

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  16. 16 Calculating molar volumes of gases • The molar volume is the volume occupied by one mole of ideal gas at STP. • Its value is: 22.414 L/mol ..so 1 mol of any gas has a volume of 22.4 L… @ STP Standard Pressure = 1 atm Standard Temperature = 0 deg C (273 K) 1 mol 22.4 L Goals: Apply concepts of the mole and Avogadro’s number to conceptualize and calculate molar volumes of gases

  17. 17 molar volumes of gasesPractice Problems 2 H2O2 (l) ---> 2 H2O (g) + O2 (g) Decompose 1.1 g of H2O2 in a flask with a volume of 2.50 L. What is the volume of O2 at STP? 1.1 gH2O2 1 mol H2O2 1 mol O2 22.4 L O2 34 g H2O2 2 mol H2O2 1 mol O2 = 0.36 L O2 at STP Cool Fact: Bombardier beetle uses decomposition of hydrogen peroxide to defend itself.

  18. 18 molar volumes of gases 224 liters • What volume is occupied by 10 moles of ammonia, NH3, at standard conditions? • What is the volume occupied by 40 grams of argon gas (Ar) at standard conditions? • What volume, in liters, is occupied by 1.5 x 1023 atoms of argon gas (Ar) at STP? • What volume would be occupied by 120 grams of argon gas (Ar) at standard conditions? • What volume will 0.750 moles of nitrogen gas occupy at STP? • How many moles are contained in 2.500 liters of methane (CH4) at STP? 22.4 liters 5.6 liters 67.2 liters 16.8 L N2 0.112 mol CH4

  19. 19 C3H8 (g) + 5 O2 (g)  3 CO2 (g) + 4 H2O (g) • What mass of H2O is produced if 50.0% of CO2 is produced at STP? • How many moles of gas are present in 11.2 L at STP? How many molecules? 3. How many molecules of O2 are present in 56.0L at STP? 56L 1 mol 6.022 x 1023 molecules = 22.4 L 1 mol 4. A sample of carbon dioxide gas (CO2) contains 6 x 1022 molecules. How many moles of carbon dioxide does this represent? 1/10 mole

  20. 20 Heat Flow and Temperature Change

  21. 21 Measuring Heat • Heat is a form of energy, and it is measure in Joules or Calories. • Calorie; the quanity of heat needs to raise the temperature of 1g of pure water 1˚C. • Note: Dietary Calorie is actually 1kcal.

  22. 22 Heat flows from WARMER to COLDER!

  23. Specific Heat Adding Energy to a material Causes the… Temperature to go up. Taking energy away from a substance causes the temp. to… Go down! 23 Which would heat up faster? The aluminum or the plastic? Specific means “certain”

  24. Have you ever noticed that on a hotsummer day the pool is coolerthan the hot cement? OR maybe that the ocean is cooler than the hotsand? Why? The sun has been beating down on (delivering energy to) both of them for the same amount of time.....same amount of energy. It takes more thermal energy to raise the temperature of water that it does the cement! 24

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  27. Specific Heat The amount of energy required to raise the temperature of a material (substance). It takes different amts of energy to make the same temp change in different substances. We call the amt required: Specific Heat! 27

  28. Every materials requires a different amount of energy to change its temperature. 28 (Cp) Cp Stands for “Heat Capacity” Note: The lower the number, the FASTER the material heats up….and cools down

  29. Specific Heat of water The Cp is high because H2O mols. form strong bonds w/each other. It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP). 29

  30. 18 30 Calculating Amount of Heat p The Greek letter Δ means “change in”

  31. EXAMPLE : What amount of heat is required to raise the temperature of 85.9 kg of water by 7C? The specific heat of water is 4.184 J/gC. Mass = 85.9kg Q = ? Δt = 7° Cp = 4.184 J/g-C? Q =m x Cp x Δt Q= (85.9kg)(4.184 J/g-C)(7°C) Q= 2515.8 J (WHAT DOES THAT MEAN?) 31

  32. Can you get a negative “Q” 32 Q =m x Cp x Δt Yes. If the object is LOSING heat.

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  34. Specific Heat Practice with a friend…. 3.9 x 104 J • How much heat must be absorbed by 375 grams of water to raise its temperature by 25° C? • How much energy (in calories and in Joules) will it take to raise the temperature of 75.0 g of water from 20.0 to 55.0 oC? • What is the heat in Joules required to raise the temperature of 25 grams of water from 0 °C to 100 °C? What is the heat in calories? • It takes 487.5 J to heat 25 grams of copper from 25 °C to 75 °C. What is the specific heat in Joules/g·°C? • 350 J are released as ice ( Specific Heat = 2.1 J / (g oC) ) cools from - 5.0 oC to -32 oC. What is the mass of ice? 2630 cal and 1.1 x 10 4 J 10450 J or 2500 calories 0.39 J/g·°C. 6.2 g 34

  35. 35 Changing State

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  38. 38 Sublimation • Some substances go from the solid state directly to the gaseous state.This happens when a substance was below it freezing point and is suddenly moved to a location where it is above its boiling point • EX: CO2

  39. 39 Boiling Point and Pressure • Water boils at about 95 degrees C in Denver and higher than 100 degrees C in a pressure cooker.

  40. 40 • It takes energy to cause phase changes( soild-liq-gas) • Removal of energy (gas-liq-solid) Increase Energy Phase changes do not change the substance Clip

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  42. 42 • The amount of energy required for a substance to go from a solid to a liquid is called the HEAT OF FUSION. • (EX) it takes 334,000 Joules of energy to melt 1 kg of ice. No temperature change. 0°C 0°C NO TEMP CHANGE

  43. 43 • The amount of energy required to change a liquid to a gas is called the …Heat of Vaporization • EX: It takes 2,260,000 Joules of energy to vaporize 1 kg of water. 100 °C 100 °C NO TEMP CHANGE

  44. 44 Information: H20 Heat of Fusion (hf) = 334 J/g Heat of vaporization (hv) =2260 J/g Practice Problems • What is the heat in Joules required to convert 25 grams of water into steam? What is the heat in calories? • What is the heat in Joules required to melt 25 grams of ice? What is the heat in calories? • How much energy would be required to melt 15.0 g of ice at 0 oC? • How much energy would it take to boil 36.0 g of water at 100 oC? • 56425 J, 13,500 cal • 8350 Joules or 2000 cal 5.01 KJ 81.4 KJ

  45. 45 Combination Problems….You can do this  • How much energy would it take to melt 30.0 g of ice at 0 oC and warm the resulting liquid to 35.0 oC? • 14.4 KJ • How much energy would it take to warm 30.0 g of water at 35 oC to the boiling point and boil all the liquid away? • 76 KJ • How much energy would be reqired to melt 10.0 g of ice at 0 oC, warm the resulting liquid to 100 oC, and change it to steam at 100 oC? • 30.1 KJ

  46. 46 • Phase depends not only on temp. but also pressure. • The triple point of a substance is the temp. and pressure at which the three phases of that substance coexist

  47. 47 • Phase depends not only on temp. but also pressure.

  48. 48 When heat is added to most materials they expand. Thermal Expansion • When objects are heated, they expand. • When they are cooled, they contract. • Video Clip

  49. 49 Thermal Expansion • Thermometers: Work because of thermal expansion. Typical expansion joints on a steel span bridge.

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