Solutions & colloids

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  • p.156 top, 7 th Ed., 2010
  • There are names for each of the possible eight types of colloids.
  • Solutions & colloids

    1. 1. <ul><li>“ Pollution ” by Tom Lehrer </li></ul><ul><li>  </li></ul><ul><li>Time was when an American about to go abroad would be warned by his friends or the guidebooks not to drink the water, </li></ul><ul><li>but times have changed and now a foreigner coming to this country might be offered the following advice: </li></ul><ul><li>  </li></ul><ul><li>If you visit American city, You will find it very pretty </li></ul><ul><li>Just two things of which you must beware: Don't drink the water and don't breathe the air </li></ul><ul><li>  </li></ul><ul><li>Pollution, pollution, They got smog and sewage and mud </li></ul><ul><li>Turn on your tap And get hot and cold running crud </li></ul><ul><li>  </li></ul><ul><li>See the halibuts and the sturgeons being wiped out by detergents </li></ul><ul><li>Fish gotta swim and birds gotta fly, but they don't last long if they try </li></ul><ul><li>  </li></ul><ul><li>Pollution, pollution. You can use the latest toothpaste </li></ul><ul><li>And then rinse your mouth with industrial waste </li></ul><ul><li>  </li></ul><ul><li>Just go out for a breath of air and you'll be ready for Medicare </li></ul><ul><li>The city streets are really quite a thrill: If the hoods don't get you, the monoxide will. </li></ul><ul><li>  </li></ul><ul><li>Pollution, pollution. Wear a gas mask and a veil </li></ul><ul><li>Then you can breathe, long as you don't inhale. </li></ul><ul><li>  </li></ul><ul><li>Lots of things there that you can drink but stay away from the kitchen sink </li></ul><ul><li>The breakfast garbage that you throw in to the bay, they drink as lunch in San José. </li></ul><ul><li>  </li></ul><ul><li>So go to the city, see the crazy people there: Like lambs to the slaughter </li></ul><ul><li>They're drinking the water and breathing [ cough] the air. </li></ul>
    2. 2. Solutions and Colloids
    3. 3. Solutions definition
    4. 4. Solutions
    5. 5. 9 (actually 7 or 5) types of solutions
    6. 6. Solution is a dynamic equilibrium process as a balance of dissolving and precipitating
    7. 7. Why do substances dissolve? (potential solutes)
    8. 9. Thermodynamic parts of the dissolving process
    9. 10. Energy diagram for dissolving
    10. 11. Change in solubility with Temperature for gaseous solutes for solid (ionic) solutes Heat to “de-gas” solutions A beaker of cold tap water develops air bubbles as it warms to room temperature. Most ionic solutes increase in solubility as temperature increases
    11. 12. Effects of pressure of solubility of gases
    12. 13. A sample problem & applications of Henry’s Law
    13. 14. Some reasons to learn about solubilities (Uses and Applications of Solubility)
    14. 15. Miscible and Immiscible Water and alcohol are miscible. Oil-and-water is an immiscible system.
    15. 16. Classification of solvents
    16. 17. As the organic alcohol part of the molecule is shortened, the solubility in water increases and the solubility of NaCl in the alcohol increases (see below).
    17. 18. Ionic solids dissolve in water because they become hydrated by water
    18. 19. Hydration of ions provides the energy of hydration which is the main exothermic part of the energy of dissolving
    19. 20. Colloidal Dispersions Suspension or under microscope beyond microscope
    20. 21. Eight types of Colloids (out of a possible 9) with names
    21. 22. Properties of Colloids
    22. 23. Tyndall effect Projector’s Light off Projector’s White light on Light beam is invisible in a true solution, but the beam is seen when it passes through any colloidal dispersion because the light is scattered by the colloidal-sized “micro-droplets” (Rayleigh scattering). Whenever you can see a beam of light (like the headlight beam of a car) it is due to the Tyndall effect through fog, mist, smoke or other colloid . Laser beam visible in a colloidal dispersion.
    23. 24. Brownian motion discovered by botanist, Robert Brown, 1827 <ul><li>http://groups.physics.umn.edu/demo/thermo/movies/4D1020.mov </li></ul><ul><li>http://www.youtube.com/watch?v=4tt7M2fpI6U </li></ul>To show Brownian motion, the ”micro-droplets” must be large enough that the microscope can see them, yet those “micro-droplets” must be small enough that they are visibly jostled or moved by the impacts of the surrounding unseen molecules. Brownian motion and Tyndall effect are characteristics of colloids. Under a microscope, any colloidal sized “micro-droplets” are seen to move around in a random dance.
    24. 27. Colloidal silver: an alleged antibiotic
    25. 30. Salt-in-water solutions of different concentrations Dilute 0.01 molar = 0.01 M = 0.01 moles/Liter Not so dilute 0.1 molar = 0.1 M Concentrated 0.6 molar = 0.6 M (seawater) = 3.5 % = 3.5 grams/Liter
    26. 32. Unsaturated, Saturated, and Supersaturated
    27. 33. Pictures taken seconds apart after a seed crystal of Na 2 SO 4 is dropped into a supersaturated solution of Na 2 SO 4
    28. 34. Supercooled glacial acetic acid
    29. 35. Four aspects of concentration units
    30. 37. Higher concentration does not always give a stronger effect
    31. 38. Part-per-Whole Ratio
    32. 39. Percentage calculations
    33. 40. Mole fraction
    34. 42. Definitions of the main concentration units used in chemistry
    35. 43. What to write, say, and think
    36. 45. Advantages and Disadvantages of each of the main concentration units
    37. 46. Some reasons to learn about concentration units (and their calculations)
    38. 47. Steps to prepare a solution
    39. 48. Preparation of a solution of known concentration
    40. 49. Problem on How to Prepare a Solution
    41. 50. Labeling a solution
    42. 51. Bottle labels usually do not list the full ionic composition
    43. 52. How to convert concentration units
    44. 53. Converting concentration units (continued)
    45. 54. Converting concentration units
    46. 55. Calculations for dilution of solutions
    47. 56. Before dilution After dilution
    48. 57. Calculations for mixing of solutions
    49. 58. Ten-fold serial dilution of potassium permanganate
    50. 60. Solution Stoichiometry
    51. 61. Titration stoichiometry Here A is for acid, and B is for base.
    52. 62. Limiting Reactant using solutions
    53. 63. More solution stoichiometry Q: If 37 mL of 0.52 M dichromate react with excess methanol, CH 3 OH, how many moles of formaldehyde will be formed if the dichromate is completely used up?
    54. 64. Highest & Lowest Possible Concentrations
    55. 65. Solution terminology
    56. 66. Solutions outline

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