ch 17 Flashcards

1
Q

homogenous mixture

A

can be any phase
ex. gas/gas

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2
Q

solution

A

solute + solvent

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3
Q

colligative properties

A

physical properties that depend on # of solute particles

  1. boiling point elevation
  2. freezing point depression
  3. osmotic pressure
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4
Q

boiling point elevation

A

when we add a nonvolatile solute to a solution boiling point increases
nonvolatile solutes dont evaporate easily (sits in and above liquid and prevents liquid from turning to gas)

lowers vapor pressure and increases boiling point

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5
Q

osmotic pressure

A

pressure required to stop the flow of solvent from low to high concentration
when osmosis stops, same osmotic pressure = isotonic

pi = iMRT

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6
Q

solubility rule

A

like dissolves like
nonpolar/nonpolar
polar/polar

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7
Q

thermodynamics of solute formation

A
  1. expanding solute –> break up and expand –> delta H (+)
  2. expand solvent –> (delta H (+)
  3. mix solute and solvent usually delta H (-)
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8
Q

factors affecting solubility

A

saturation of soln
temperature
pressure

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9
Q

how does saturation affect solunility

A

saturated = soln holding max # of solute
unsat. = soln holding less than max amount
supersat = soln holding more than max solute

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10
Q

how temp afffects solubility

A

solids : as temp increases solubility increases
gases : as temp increases KE of gas molecules increase and thus they can escape the liquid more, so solubility decreases

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11
Q

how does pressure affect solubility

A

henry’s law
P = kmX (x= mole fractin
when pressure increases. more gas dissolves into liquid

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12
Q

vapor pressure

A

pressure exerted by vapor of a liquid or solid
volatile : high VP, evaporates easily, low BP
nonvolatile: low VP , doesn’t evPORATE easily

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13
Q

what happens if you mix a volatile solvent and a nonvolatile solute

A

BP increases and VP decreases
gas is trapped by solute

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14
Q

raoult’s law

A

Psoln = Xsolvent*Psolvent

only solvent contributes to VP

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15
Q

what happens if you mic a volatile and volatile

A

both contribute to VP

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16
Q

deviations from raoult’s law

A

no interactions: ideal soln. (nonpolar/nonpolar) –> VP as expected delta H = 0

unfavorable interactions–> repulsions–> polar and nonpolar –> VP higher than expected, positive deviation delta H (+)

favorable interactions –> polar and polar –> solution interactions stronger than components interactions –> VP lower than expected, delta H(-)