Chem Chapeter 13

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Tiye
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139939
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Chem Chapeter 13
Updated:
2012-03-09 16:32:03
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Chapter 13 General chem
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  1. Like dissolves?
    LIKE....fuck ya
  2. Unlike interactions > Like interactions?
    Exothermic overall
  3. Unlike interactions ~~Like interactions
    Ideal mixture
  4. Unlike interactions < Like interactions:
    • – endothermic overall
    • – or heterogeneous mixture
  5. When does condensation rate = evaporation rate
    at vapour pressure
  6. recrystallization rate = dissolution rate when?
    at saturated solution
  7. When does solubility increases for most ionic solids?
    With increasing temperature
  8. how is Supersaturated solution is obtained?
    by coolingor concentrating a saturated solution.
  9. Recrystallization is nucleated?
    must add a few crystals of solute to initiate.
  10. Fractional Crystallization?
    • Purify a compound fromsmall amounts ofimpurities
    • • Cool the solution –desired compoundbecomessupersaturated,crystallizes.
    • • Impurities areunsaturated, do notcrystallize.
  11. Saturated Solution: maximumconcentration of dissolved solute.
    rate of dissolution = rate ofcrystallization
  12. What can fractional crystalization can be used as?
    Purification step
  13. Solubility of gasses in water generally_______with increasing temperature
    decreases
  14. Why does solubility of gasses decrease with increasing temperature?
    many organisms prefer cooler water.– one projected effect of global warming isa decrease in dissolved oxygen in oceans
  15. Solubilities of gases_______with increased pressure ofthe gas above thesolvent.
    increases
  16. What is henry's law??
    C = k * Pgas
  17. Increasing the pressure_______ the rate ofcondensation into the liquid:increased concentration.
  18. Concentration reachesdynamic equilibrium,(evaporation rate =condensation rate) when?
    C = kPgas
  19. Solubility of CO2in water is ____under highpressure.
    high
  20. Raoult’s Law?
    The vapor above an ideal solution isenriched in the more volatile component.
  21. Fractional Distillation?
    purify the volatile component through iterative evaporation,separation and condensation
  22. Non-ideal solutions can lead to?
    • azeotropes
    • – mixtures where the vapor and liquid phaseshave the same composition.
  23. Osmosis?
    solvent flows across semipermeable membranes to the sidewith solute.
  24. The pressure required to stoposmotic flow is?
    the osmoticpressure: pi = MRT
  25. Applying pressure >  reversesdirection of flow: _______osmosis?
    • reverses osmosis
    • concentrate solutes, purify solvents.
  26. Osmotic pressure depends on the?
    • concentration of solute particles.– similar to ideal gas equation
    • piV = nRT?
  27. Lower vapour pressure leads to?
    • higher boiling points.– liquid phase favoured over vapor phase
    • PA=xAP°vap
  28. Colligative Properties?
    • properties of dilute solutions of non-volatile solutes that depend only on concentration, not onindividual properties
    • • osmotic pressure
    • • freezing point depression
    • • boiling point elevation
  29. What makes a substance an electrolyte?
    • • conduct electricity
    • • anomalous colligative properties
    • • contain dissolved ions
  30. Van’t Hoff factor?
    • • i = ΔTobserved÷ΔTpredicted
    • • effective moles of dissolvedparticles per mole of solute
  31. Which affect gases more temp or pressure?
    pressure
  32. What is henry's constant?
    1.3e-3Matm-1
  33. The boiling point of a solution made of a liquid solvent with a nonvolatile solute is________than the boiling point of the pure solvent?
    greater
  34. Boiling point of liquid is?
    The temperature at which the vapour pressure of that liquid is equal to the atmospheric pressure
  35. What are example of non electrolytes?
    sugar, benzene, phenol, water
  36. Whats i ( van't hoff factor) for nonelectrolytes?
    1
  37. What is an example of an electrolyte and what is its van't hoff factor?
    i=2 and NaCl, KI, MgO
  38. What is an example of a strong electrolyte and what is it Van't Hoff factor?
    i=3 and MgCl2, Na2SO4
  39. What is the equation for Boiling point elevation?
    ΔTb = iKbm

    • i=van't hoff factor
    • Kb=boiling point elevation constant
    • m=molality
  40. Why is freezing point depressed?
    Due to the vapour pressure lowering phenomenon
  41. Why is th freezing point negative in the freezing point depression formula?
    Because the freeing point of the solution is less than that of the pure solvent
  42. Why do we use molality to measure the concentration of the solute?
    Because molality is temperature independent
  43. Why is a solution more difficult to freeze than the pure solvent?
    Because in order to freeze a liquid it must achieve a very ordered state that results in the formation of a crystal. If there are impuritities in the liquid, ie solutes, the liquid becomes less ordered.
  44. Freezing Point Depression formula?
    ΔTf = -iKfm

    • i=van't hoff factor
    • Kf=boiling point elevation constant
    • m=molality

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