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Things To Do Now:

Things To Do Now:. Hot, Cold, & Sublime. Unit 3: Phases of Matter Lesson 1: Phases and Phase Change. It’s all about Charges. We talk about “charges” in chemistry...a lot! Charges are electrical forces Charges are either positive (+) or negative (-)

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Things To Do Now:

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  1. Things To Do Now:

  2. Hot, Cold, & Sublime Unit 3: Phases of Matter Lesson 1: Phases and Phase Change

  3. It’s all about Charges We talk about “charges” in chemistry...a lot! Charges are electrical forces Charges are either positive (+) or negative (-) Opposite charges attract, like charges repel.

  4. Intermolecular Attractive Forces Intermolecular Attractive Forces= Any forces (charges) that work to hold particles of a substance together. Stronger Intermolecular forces = The more energy needed to separate the particles of a substance.

  5. Phases of Matter There are 3 phases of matter (on Earth, normally): • Solids • Liquids • Gasses These are arranged in order of distance between particles. How do you move between phases of a substance?

  6. Solids Highly Scientific Particle Diagram of A Solid Particles are arranged into a regular, geometric pattern (a crystal lattice). Particles vibrate in place. Substance has a definite shape & a definite volume.

  7. Liquids Highly Scientific Particle Diagram of A liquid Particles can flow past each other. Resistance to flow is called viscosity. Viscosity increases as temperature decreases and IMAF strength increases. Evaporation- liquid particles escape into the gas phase below the boiling point. Take the shape of the container, definite volume.

  8. Gasses Highly Scientific Particle Diagram of A Gas Gas particles are extremely far apart. Gas particles travel in a straight line until they collide. Collisions are elastic which means they don’t lose any energy or speed. Gas particles move faster when it’s hotter (higher Kelvin temperature) The only phase that is affected by changes in pressure. Takes the shape and volume of whatever container they are put into.

  9. Phase Change Diagram (Learn It!) Endothermic Sublimation Melting Vaporization S L G Freezing Condensation Deposition Exothermic Melting = “Fusion” Freezing = “Solidification”

  10. Equilibrium Any time the rates of opposing processes are equal, those processes are said to be in equilibrium. Phase Equilibrium: Exists at a substances melting point (for solid and liquid phases), and boiling point (for liquid and gas phases). What’s in equilibrium at these temps?

  11. Sublimation Highly Scientific Sublimation Particle Diagram Can happen in a lot of substances. Most noticeable in substances that have very weak Intermolecular Attractive Forces.

  12. Heating Curves A characteristic graph that you get when heating a substance from a solid to a gas.

  13. A Few Questions Why isn’t the temperature increasing during phase changes? Why does it take longer to go from liquid to gas than from solid to liquid? What would a cooling curve look like?

  14. Water’s Heating Curve What is water’s melting point in Kelvin? What is its boiling point?

  15. Questions You Need To Answer How many minutes pass from the first appearance of the liquid phase until the substance is entirely in the gas phase?

  16. How many minutes will it take for this substance to undergo melting?

  17. For how many minutes is the water completely in a phase made of a crystal lattice?

  18. What line segment represents when H2O is both in the liquid AND the gas phase?

  19. For how many minutes is the water completely in a phase with no definite shape or volume?

  20. How many minutes will it take for the water to boil, once the boiling point temperature has been reached?

  21. Heat Me Up, Cool Me Down, Just Please, Ask me questions!!! What now?

  22. Things To Do Now:

  23. Behold! Unit 3: Phases of Matter Lesson 2: Energy Required for Phase Change

  24. Consider Melting & Boiling. What happens during each? Endothermic or exothermic?

  25. Consider Freezing & Condensing. What happens during each? Endothermic or exothermic?

  26. Heat of Fusion (Hf) What is water’s melting point? Hf of H2O = 334 J/g The amount of heat needed to melt one gram of a substance at its melting point. ALSO...The amount of heat needed to be removed from one gram of a substance at its freezing point. This is on Table B of your Reference Tables.

  27. Fun With Hf q = mHf m = mass of substance in grams We can use Hfto calculate how much heat is needed to melt any amount of a substance AND how much heat is released when any amount of a substance freezes This is on Table T of your Reference Tables.

  28. How many joules does it take to melt 100. grams of water at its melting point?

  29. How many joules does it take to freeze 50.0 grams of water at its freezing point?

  30. Heat of Vaporization (Hv) What is water’s boiling point? Hv of H2O = 2260 J/g The amount of heat needed to boil one gram of a substance at its boiling point. ALSO The amount of heat needed to be removed from one gram of a substance to freeze it at its freezing point. This is also on Table B of your Reference Tables.

  31. Fun With Hv q = mHv m = mass of substance in grams We can use Hvto calculate how much heat is needed to melt any amount of a substance AND how much heat is released when any amount of a substance condenses This is also on Table T of your Reference Tables.

  32. How many joules are required to boil 100. grams of water at its boiling point?

  33. How many joules does it take to condense 50.0 grams of water at its boiling point?

  34. Putting It All Together How many joules are required to heat 100.0 grams of H2O (s) from –20.00oC to 130.00oC? Visualize What’s Happening: PS- C(ice) & C(steam) ≅ 2.09 J/g°C

  35. Multiple Equations Are Required 1. 3. 4. 5. 2. What do we do next? q = mC(ice) ΔT q = mHf q = mC(water) ΔT q = mHv q = mC(steam) ΔT Add It All Up!

  36. The Secrets of the Universe are Revealed!!! Any Questions? What now?

  37. Things To Do Now:

  38. Why Balloons Float(and why they don’t) Unit 3: Phases of Matter Lesson 3: Gasses and Pressure

  39. How does a gas behave? Kinetic Molecular Theory (KMT)- Describes an “ideal” gas. We imagine how it would behave. It would have five properties: Be made of particles with negligible volume Particles move in random, straight-lines Completely elastic collisions No intermolecular attractive forces Speed of particles is directly proportional to Kelvin temperature

  40. Ideal is not Real When would this happen? Real gasses violate some/all of the KMT But- Only when the particles are moving slow and are squeezed together. Low Temperature & High Pressure = Non-Ideal Behavior

  41. Avogadro’s Hypothesis Equal numbers of gas particles occupy equal volumes of space under the same conditions of temperature and pressure. They all contain equal numbers of molecules!!! Amedeo Avogadro (1776 – 1856) How can this be?!?

  42. Standard Temperature and Pressure (STP) Because things happen differently at different temperatures and pressures (particularly for gasses), we have to set a standard reference point. Standard Temperature: 0° C = 273 K Standard Pressure: 1.000 atm = 101.3 kPa = 760 mmHg (torr) These are in Reference Table A.

  43. What is this “Pressure” of which we speak Pressure = Force exerted over an area. Anything with mass can exert a force. This includes the atmosphere. Standard Pressure: 1 atmosphere of pressure (at sea level)= 14.7 pounds per square inch (psi).

  44. Brief notes on Torr. Why do we use mercury? Evangelista Torricelli (1608 – 1647) Torr = millimeters of mercury (mmHg) Refers to the column of mercury in a barometer. 760 torr = Standard pressure

  45. Pressure conversions Convert 2.35 atm to kPa: Convert 1.234 kPa to atm: 1.000 atm = 14.7 psi = 101.3 kPa = 760.0 mmHg

  46. Vapor Pressure When a liquid in a sealed container is at vapor-liquid equilibrium, the vapor exerts a pressure (like any gas). Stronger IMAF = Lower vapor pressure. Higher vapor pressure = faster rate of evaporation. Volatile= Substances that evaporate quickly.

  47. Why do things boil? How Can you increase vapor pressure? Boiling happens when the vapor pressure of a liquid is greater than the atmospheric pressure the liquid is under. Boiling Point = Vapor pressure = atmospheric pressure.

  48. Normal Boiling Point The boiling point of a liquid at Standard Atmospheric Pressure. What happens to boiling point if atmospheric pressure increases? Decreases?

  49. Reference Table H

  50. Use Method A! Problem: What is the vapor pressure of ___ at ___°C?

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