Chem Ch12

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Chem Ch12
2011-02-10 17:03:07
chem ch12

Chapter 12 material
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  1. What is a heterogeneous solution?
    A solution with components that have observable boundaries, i.e. sand in water.
  2. What is a homogenous solution?
    Soultion that is uniform in appearance, with no observable boundaries, i.e. sweet tea.
  3. Define solubility.
    How much solute can be dissolved in a given emount of solvent.
  4. What is another word for solvation? Define it.
    Dissolution. Action of components dispersing at a molecular level.
  5. Define entrophy.
    The measure of the dispersal of energy in a system. The more spread out = the higher entrophy.
  6. What are the energetics required for a solution to form?
    -ΔH mix >= ΔH solvent + ΔH solute

    -Sometimes ΔH mix can be less than ΔH solvent + ΔH solute, but would depend on the intermolecular forces in the solvent & solute.
  7. When is a reaction exo- or endothermic?
    • ΔH mix > ΔH solvent + ΔH solute then reaction is exothermic
    • ΔH mix < ΔH solvent + ΔH solute the reaction is endothermic.
  8. What is a saturated solution?
    Solution where undissolved solute is in equilibrium with dissolved solute.
  9. What is a supersaturated solution?
    A solution that has more solute dissolved than solubility will allow - usually because of increased temperatures.
  10. What is an isothermic reaction?
    Reaction where ΔH mix = ΔH solvent + ΔH solute.
  11. What needs to be considered for any process to occur?
    Enthalphy and entrophy.
  12. What is the formula for molality?
    m = mol solute/kg. solvent
  13. What is the formula for mole fraction? Mole percent?
    χ = mol solute/(mol solute + mol solvent)

    mol % = mol solute/(mol solute + mol solvent) * 100
  14. What is the formula for parts by mass? Also applies to volume.
    mass solute/mass solution * multiplication factor

    • percent by mass (%): 100
    • ppm: 106
    • ppb: 109
  15. What are the colligative properties?
    • Vapor pressure lowering
    • Freezing point depression
    • Boiling point elevation
    • Osmotic pressure
  16. Define colligative property.
    A property that depends on the number of particles in a solution, not on the type of particle.
  17. What is the formula used when both solute and solvent are volatile?
    P soln = χ solv ( P0 solv)
  18. What is the formula to determine boiling point elevation and freezing point depression?
    Tb = imKb and Tf = imKf
  19. What is the formula to determine osmotic pressure?
    π = iMRT