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68 Cards in this Set

  • Front
  • Back
when clamping an apparatus, start from the . . .
bottom up
what are the baby clamps called
Keck clamps
purpose of boiling chips
to moderate reflux and prevent bumping
how far should you let the liquid rise up the condenser
1/3 of the way
to heat to 100 degrees, use . . . and more than 100 degrees . . .
steam bath, heating mantle
three commonly used drying agents
anhydrous calcium sulfate, anhydrous calcium chloride, anhydrous magnesium sulfate
how tall should the amount of sample in the m.p. capillary be
2-3 mm
after the first m.p. test, how low should you let the temp of the Mel-temp drop before performing the second
at least 15 degrees below the estimated m.p.
what solvent was used in the who has my compound experiment to test for solubility
sodium bicarbonate
two adsorbents frequently used in TLC
silica gel or alumina
how is the adsorbent stuck to the TLC plate
a small amount of inorganic binder is mixed in
why does the TLC fluoresce under UV light?
an inert inorganic material that fluoresces is mixed in with the adsorbent and binder
why must we be careful with the silica gel and alumina used in TLC
it is abrasive and can scratch your eyes
the developing solvent used in TLC chamber
50/50 mixture of ethyl acetate/hexanes
Rf stands for
retention factor or ratio of fronts
what kind of melting point range indicates that the compound is impure
a range greater than 2 degrees C
why does the presence of impurities lower the melting temp
it increases entropy and lowers the energy required to melt the compound
eutectic point
the lowest m.p. observed for any mixture of two components. it's a sharp melting point
what's the H-C-H angle in methane (CH4)
109 degrees
how can you tell whether you have enough of your unknown on your tlc plate
visualize with the uv lamp
how many atoms will be attached to an sp-hybridized carbon atom
2
T or F, latex gloves are useful w/ organic chemicals
false
what can you deduce if your compound dissolves in sodium bicarbonate solution
my compound is an acid
which is the most efficient technique for removing suspended solid impurities prior to recrystallization
hot vacuum filtration
what was the name of the compound recrystallized in Recrystallization
acetanilide
molecular formula of sodium bicarbonate
NaHCO3
what is a disadvantage of recrystallization
loss of product
why is it important to place the recrystallization solution in an ice-water bath after it has reached room temp
it will help to increase recovery of crystals
the torsion angle is also called the
dihedral angle
what solvent is used to dissolve acetanilide
water
true or false? recrystallization is a good purification technique
false
what should you do if your solution oils out (Recrystallization)
add more solvent to redissolve the oil
when the dihedral angle between two groups is 180 degrees, what is the name of the conformation
anti
what will IR radiation not pass thru
glass
three advantages of Attenuated Total Reflectance (ATR) in IR
being able to collect a spectrum despite only having a minute sample

being able to collect a spectrum of a solid

being able to collect a spectrum of a liquid
conformations of a molecule can be formed by . . .
making and breaking of bonds
in the Extraction experiment the final product is isolated as a solid/liquid/gas/ionic salt?
solid
the normally scanned range in cm-1 for IR is
400-4000
in Extraction, why would the phenol layer ever be on top of the water?
if you have a lot of salts dissolved in the water and it becomes more dense than the phenol
define a wavenumber
the number of waves that fit in a certain distance
is IR destructive or non-destructive
non
a c=o stretch can be found around...
1700 cm-1
the selection rule to observe an active IR band:
change in dipole moment
from which layer of an extraction using dichloromethane and aqueous sodium bicarbonate could benzoic acid be isolated?
dichloromethane layer
when comparing the relative amounts of two or more compounds eluted from a GC, one should compare...
the peak area ratio
a requirement of a molecule for it to be purified by distillation
must be heat-stable
three reasons dichloromethane was used as the organic solvent in Extraction
it is immiscible with water

it does not react with any of the compounds in the sample

it dissolves all of the compounds in the sample
we need to inject ____ microliters of the sample mixture into the GC
40
in the TLC experiment, the solid sample is dissolved in . . .
methanol
simple distillation fails for compounds that are . . .
non-volatile
a GC column separates mixture based upon . . .
compound-stationary phase interaction
for TLC, the stationary phase is usually ____ and the mobile phase is usually _____
polar, nonpolar
bp of a liquid is the temp at which
the vapor pressure equals the atmospheric pressure
what feature of a GC would indicate a pure sample
a single peak
why do we seal the TLC jar
to prevent the solvent from evaporating
potassium permanganate reacts with . . .
akenes and alkynes
if a polar mixture of two substances with similar boiling points is injected into a GC packed wiht carbowax (a polymeric alcohol), they will separate based on volatility and _____
polarity
what part of the spot do we measure for Rf value
middle
eugenol, a component of clove oil, has been widely used as ______
a dental analgesic
eugenol will be extracted from a dichloromethane solution by treating with ______ to make a water soluble salt
NaOH
aspirin, acetominophen, and ibuprofen are all part of a common class of pain relief agents called:
analgesics
_______ is a process that can be used for separating temp-sensitive natural products like limonene from citrus peels
steam distillation
why would phenol not be a good solvent for Phase Transfer
it will react w/ the alyl bromide
in extraction, what should you do if you observe an emulsion
add more water
which is a common phase transfer catalyst
Benzyl tri-n-butylammonium chloride
requirement for steam distillation
material must be immiscible in water
which are more constant, upper or lower mp range values
upper
darkening
an obvious color change by the material in a capillary tube when heating