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Phases of Matter and Solutions

Phases of Matter and Solutions. Mr. Nylen Chemistry. Review of Calorimetry. Worksheet – Reviewing what we know. Use worksheet to help you review Solids Liquids Gases For help look to: Review book – page 45 Text page 6-7 – Solids, liquids, and gases are states of matter

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Phases of Matter and Solutions

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  1. Phases of Matter and Solutions Mr. NylenChemistry

  2. Review of Calorimetry

  3. Worksheet – Reviewing what we know • Use worksheet to help you review • Solids • Liquids • Gases • For help look to: • Review book – page 45 • Text page 6-7 – Solids, liquids, and gases are states of matter • Pages 424-426 – Properties of gases • Page 443 – Paragraph next to brown bottle

  4. Comparison of phases at the molecular level (p. 1) Solids Liquids Gases

  5. Comparison of Phases (p. 1-2)

  6. Comparison of Phases (p. 1-2)

  7. Additional Physical Properties • Solids – usually have a crystalline structures • Regular repeating geometric arrangement of atoms • Liquids – Exhibit unique properties such as: • volatility (ability to evaporate) • Viscosity (resistance to flowing) • Surface tension (ability of particles to hold together) As the forces of attraction between particles in a liquid increase, the volatility decreases, the viscosity increases, and the surface tension increases

  8. Amorphous Solids • Super cooled liquids – • Liquids that appear to be solid but yet they do flow slowly over time when force is applied. They have no observable crystalline structure. Examples include some plastics, rubber, butter, and amorphous sulfur.

  9. Viscosity of amorphous solids • The viscosity (resistance to flow) of amorphous materials increases with decreasing temperature and decreases with increasing temperature • Vegetable oil is too think to run in cars, so you have to heat it before you burn it

  10. Phase Changes and Energy • Phase change diagram Absorb energy, endothermic Solid Liquid Gas Release energy, exothermic

  11. Heat of Fusion • Amount of heat absorbed when 1g of a substance melts at its melting point • Same amount of heat as heat of crystallization • Heat of fusion = heat needed to melt a fused solid • Heat of crystallization = heat needed to fuse together a liquid 1 gram 1 gram water

  12. Heat of Fusion • Units = Joules/gram • Formula: • Hf equals heat of fusion • Look up Hf values in reference tables B • Waters is 334 J/g

  13. Heat of Vaporization • Amount of heat absorbed when 1g of a substance vaporizes at its boiling point • Same amount of heat as heat of condensation

  14. Heat of vaporization • Units: • Joules/gram • Formula • Look up heats of vaporization on table B • Waters is 2260 J/gram

  15. Heat causing temperature change • Remember that we can calculate the amount of heat needed to change the temperature of a certain mass of water • Where c is the specific heat of water (4.18) • T is temperature change • Mass is mass of water

  16. Tricks • When approaching problems, figure out if the substance is fusing (melting/freezing), vaporizing (boiling/condensing), or just changing temperature • Look up the corresponding value on the reference table and use the correct formula

  17. Practice Problems • RB pg. 65, 30-46

  18. Lab – Heat of Fusion of Ice • Calorimetry

  19. Problem Set (and Turn in Lab) • Complete the following: • Show phase changes, endo, and exo Solid Liquid Gas

  20. Review: • When approaching problems, figure out if the substance is fusing (melting/freezing), vaporizing (boiling/condensing), or just changing temperature • Look up the corresponding value on the reference table and use the correct formula

  21. Problem Set (until 12:35) • How much heat is needed to completely melt 12.45 gram of ice at 0 celcius, heat it to 100 celcius, and completely boil it? • Step 1 (melt it) • Step 2 (heat it) • Step 3 (boil it

  22. Heating Curves – pg. 8 Calculations: Heating from solid phase at 100 J/min

  23. Heating Curves and Energy Heating from solid phase at 100 J/min

  24. Notes – page 10 together

  25. Cooling Curve

  26. Notes pg. 11

  27. Try 12-13 on your own

  28. HW – review book pg. 60 • #1-16 • Some we’ve already done before

  29. Lab – Heat of crystallization of Wax

  30. HW – Due Tuesday • Pg 12 - 14 notes

  31. Review Homework • Go over page 12-14 in notes

  32. Notes pg. 15-16 • A heating curve is given • Determine the KE and PE for each interval • Remember, if KE increases, PE stays the same • Create your own cooling curve • We will be doing this again in the lab

  33. Energy, and Heating Curves

  34. Lab – Cooling Curve for Lauric Acid

  35. Homework • Finish Lab • RB pg. 47, 1-16

  36. Review Homework • Go over RB pg. 47, 1-16 • Go over Lauric Acid Lab

  37. Notes p. 17 • Work through pg. 17-18

  38. Notes p. 19-20 • Work in your lab groups to complete these questions • Put answers on separate sheet of paper and hand in with all group members’ names

  39. Review – Pg. 21-22 • Go over in class

  40. Equilibrium Vapor Pressure – Notes p. 23 • Defined: Vapor pressure is pressure exerted on the surface of a liquid or solid by particles of the substance that have changed over to vapor phase • As more particles are converted to vapor, vapor phase increases, vapor pressure increases

  41. Relationship between vapor pressure and Boiling point • Boiling – bubbles of vapor form under surface then rise to the top as liquid turns to a gas • In order to boil vapor pressure in bubble • Has to be equal to the air pressure outside • If pressure outside is greater bubble will collapse

  42. Questions: • As the pressure on the surface of a liquid decreases, the temperature at which the liquid will boil will A. Increase B. Decrease C. Remain the same • The vapor pressure of a liquid is .95 atm at 600C. The normal boiling point of the substance could be • 200C 300C 500C 700C

  43. Notes p. 24 • P. 24 together • P. 25 on your own

  44. Review IMF – complete study guide p. 27

  45. Intermolecular Forces of Attraction • Dipole-Dipole Attraction: • Dipole = polar molecule • Dipole = 2 poles, like a magnet

  46. Hydrogen Bonding • Very VeryVery strong dipole-dipole attraction • Occurs between molecules that contain hydrogen bonded to small, highly electronegative elements (F, O, N)

  47. Van der Waals Forces (Dispersion Forces) • In all molecules electrons are constantly moving • At any given instant in time MORE could end up on one side of the molecule than the other

  48. Van der Waals forces • This is the ONLY force of attraction that exists between nonpolar molecules • The more electrons, the stronger the Van der Waals forces • Ex: • F2, Cl2, Br2, I2 gas gas liquid solid

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