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Chemistry 120

Outline Dalton’s Law of Partial Pressure Vapor Pressure Intermolecular Forces Properties of Liquids Boiling Point Viscosity Surface Tension Energy and Changes of State Heat of Vaporization/Fusion Specific Heat Water Solids. Chemistry 120. Chapter 15: Gases, Liquids and Solids.

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Chemistry 120

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  1. Outline • Dalton’s Law of Partial Pressure • Vapor Pressure • Intermolecular Forces • Properties of Liquids • Boiling Point • Viscosity • Surface Tension • Energy and Changes of State • Heat of Vaporization/Fusion • Specific Heat • Water • Solids Chemistry 120 Chapter 15: Gases, Liquids and Solids

  2. The total pressure of two gases is the sum of their partial pressures. What is Dalton’s Law of Partial Pressure?

  3. What is Dalton’s Law of Partial Pressure? Fig. 15-1, p. 431

  4. Example – Dalton’s Law • The atmosphere of Venus contains the following gases: • CO2 392 torr, • N2 834 torr • Ar 302 torr • What is the atmospheric pressure on Venus?

  5. Example – Partial Pressure • A mixture of oxygen and helium is prepared for a SCUBA diver, who is going to descend 200 ft below the ocean surface. At this depth, the diver breathes a gas mixture that has a total pressure of 7.0 atm. If the partial pressure of oxygen in the tank is 1.5 atm at that depth, what is the partial pressure of helium?

  6. Figure 4-9 p106

  7. What is vapor pressure?

  8. What is vapor pressure? Figure 15-4 p438

  9. When is dynamic equilibrium reached? Figure 15-16 p446

  10. How do intermolecular forces affect vapor pressure?

  11. How are gases collected over water?

  12. Example – Gas Stoichiometry • In an experiment, zinc and excess sulfuric acid reacted and 105 mL of hydrogen gas was collected at 30 °C. The barometric pressure was 755.0 mm Hg. At a water temperature of 30 °C the partial pressure of the water vapor is 31.8 mm Hg. • What is the partial pressure of hydrogen gas? • What mass of zinc reacted with excess sulfuric acid?

  13. What are London forces? aka Induced dipole – induced dipole or Nonpolar - Nonpolar interactions

  14. Example – Intermolecular Forces • Order methane, CH4, pentane, C5H12, and ethane, C2H6, in order of increasing melting point. • CH4 < C2H6 < C5H12 • C2H6 < CH4 < C5H12 • C5H12 < C2H6 < CH4 • CH4 < C5H12 < C2H6 • Not enough information

  15. What are Dipole – Dipole forces or Polar - Polar interactions?

  16. Example – Intermolecular Forces • Which molecule has the lower melting point? • Propane, C3H8 • Methanethiol, CH3SH

  17. What types of intermolecular forces do these molecules have?

  18. What are hydrogen bonds?

  19. What kind of intermolecular forces does water have?

  20. How does hydrogen bonding work in the body? Thymine Adenine Guanine Cytosine

  21. What other types of bonding are found in proteins?

  22. Example – Intermolecular Forces • Order methanol, CH3OH, fluoromethane, CH3F, and fluorine, F2, from highest to lowest melting point. • CH3OH > F2 > CH3F • F2 > CH3F > CH3OH • CH3OH > CH3F > F2 • CH3F > F2 > CH3OH • CH3F > CH3OH > F2

  23. What are the properties of liquids? • Able to flow • Fixed shape • Variable volume • Not really compressible • Atoms/molecules are close together • Free to move beneath the surface • Moderate density • Low-moderate energy • Form heterogeneous or homogeneous mixtures • Strong attractive forces

  24. When does boiling occur? Figure 15-5 p438

  25. What is happens at the boiling point?

  26. How are vapor pressure and boiling related? Figure 15-17 p447

  27. How do intermolecular forces affect the boiling point?

  28. What is surface tension?

  29. Why does the mensicus of water curve downward? Figure 15-7 p439

  30. Figure 15-8 p439

  31. What is viscosity?

  32. What are phase transitions? Vaporization Liquid to gas transition Condensation Gas to liquid transition Melting Solid to liquid transition Freezing liquid to solid transition Sublimation Solid to gas transition Deposition Gas to solid transition

  33. Table 15-4, p. 452

  34. What is specific heat?

  35. Table 15-5, p. 455

  36. Figure 15-33 p463

  37. Example – Changes in State • Ice cubes at 0 °C with a mass of 26.0 g are added to a soft drink. How much heat in joules will be absorbed to melt all the ice at 0 °C? If DHfusis 333 J/g.

  38. Example – Changes in State • In a sauna, 122 g of water is converted to steam at 100 °C. How many kilojoules of heat are needed? If DHvap is 2.26 kJ/g.

  39. How is the energy of food measured?

  40. Example - Heat • If one stalk of celery heats 505 g of water from 25.2 °C to 35.7 °C in a calorimeter, how many kilocalories were in the unburned (uncombusted) celery? Cwater = 4.184 J/g °C

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