Chem Ch 12

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Chem Ch 12
2010-04-29 16:06:37
Chemistry Chang

Chang 12
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  1. solution
    homogeneous mixture
  2. saturated solution
    contains the maximum amount of solute that will dissolve in a given solvent at a specific temperature
  3. unsaturated solution
    contains less solute than it has the capacity to dissolve
  4. supersaturated solution
    contains more solute than is present in a saturated solution, can be formed by careful cooling, solute will separate if solution is disturbed (crystalization)
  5. solubility
    • the measure of how much solute will dissolve in a solvent at a specific temperature
    • "like dissolves like" - 2 substances with intermolecular forces of similar type and magnitude are likely to be soluble in each other
    • (non-polar will be soluble with non-polar) hydrocarbons are always non-polar
    • (polar w polar)
  6. miscible
    if substances are completely soluble in each other in all proportions
  7. concentration
    the amount of solute present in a given amount of solution
  8. molarity
    M = mol solute/ L solution
  9. percent by mass
    mass of solute/mass of solution * 100%
  10. mole fraction
    • mol of single component/moles of all components
    • Xa has no units
  11. molality
    m = moles of solute/mass of solvent (kg)
  12. solvation
    the process in which an ion or molecule is surrounded by solvent molecules arranged in a specific manner
  13. fractional crystallization
    the separation of a mixture of substances into pure components on the basis of their differing solubilities
  14. The effect temperature has on the solubility of a solid
    usually solubility increases but there are exceptions, it is best determined experimentally
  15. The effect temperature has on a gas solute
    • solubility usually decreases with increasing temperature
    • warm water is bad for fishes because the solubility of oxygen decreases
  16. Henry's law
    • the solubility of a gas in a liquid is proportional to the pressure of the gas over the solution
    • c =kP
    • if more than 1 gas present P = partial pressure
    • c = molar concentration
  17. Effect of pressure on solubility
    • doesn't change with liquids or solids
    • external pressure GREATLY INCREASES the solubility of gas
  18. colligative properties
    • (or collective properties) - properties that depend only on the # of solute particles in solution and not on the nature of the solute particles
    • 1. vapor-pressure lowering
    • 2. boiling-point elevation
    • 3. freezing-point depression
    • 4. osmotic pressure (raising)
  19. electrolyte vs. nonelectrolyte
    • electrolytes break apart into ions when they dissolve
    • nonelectrolytes do not break apart (molecular compounds or covalent compounds that aren't acids and bases)
  20. vant hoff factor
    • i - actual # of particles in soln after dissociation/# of formula units initially dissolved in solution
    • used to convert from concentration of solute to particles
    • nonelectrolytes i = 1
  21. ion pair
    one or more cations and one or more anions held together by electrostatic forces
  22. nonvolatle
    • does not have a measurable vapor pressure
    • the vapor pressure of a nonvolatile solution is always less then that of the pure solvent
  23. Raoult's law
    • P1 = X1 P1*
    • X is mole fraction of the solvent not solute
    • P1 is vapor pressure of solution
    • P1* is vapor pressure of pure solvent
    • DONT USE i
  24. volatile
    • has measurable vapor pressure
    • do Raoult's law to each substance with measureable vapor pressure
    • total pressure is sum of partial pressures
  25. boiling point
    • the temperature at which the vapor pressure equals the external atmospheric pressure
    • ^ Tb = Kb im
    • im = concentration of particles in molality
    • ^ Tb = Tb - Tb*
  26. freezing point
    • adding solute lowers it
    • freezing point depression
    • ^Tf = Tf* - Tf
    • ^Tf = Kf im
  27. osmotic pressure
    • the pressure required to stop osmosis (the selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one)
    • (cap pie) = iMRT
    • M is molarity of particles
  28. ideal solution
    any solution that obey's Raoult's law
  29. fractional distillation
    a procedure for separating liquid components of a solution based on their different boiling points
  30. isotonic solution
    two solutions of equal concentration, therefore equal osmotic pressure
  31. hypotonic solution
    unequal concentrations - this is the more dilute solution
  32. hypertonic solution
    unequal concentrations - this is the more concentrated solution
  33. colloids
    • a dispersion of particles of one substance throughout a dispersing medium made of another substance (not really a solution) does not break apart over time
    • hydrophilic - water loving - proteins
    • hydrophobic - water fearing - oil droplets