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68 Cards in this Set
- Front
- Back
when clamping an apparatus, start from the . . .
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bottom up
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what are the baby clamps called
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Keck clamps
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purpose of boiling chips
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to moderate reflux and prevent bumping
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how far should you let the liquid rise up the condenser
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1/3 of the way
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to heat to 100 degrees, use . . . and more than 100 degrees . . .
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steam bath, heating mantle
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three commonly used drying agents
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anhydrous calcium sulfate, anhydrous calcium chloride, anhydrous magnesium sulfate
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how tall should the amount of sample in the m.p. capillary be
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2-3 mm
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after the first m.p. test, how low should you let the temp of the Mel-temp drop before performing the second
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at least 15 degrees below the estimated m.p.
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what solvent was used in the who has my compound experiment to test for solubility
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sodium bicarbonate
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two adsorbents frequently used in TLC
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silica gel or alumina
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how is the adsorbent stuck to the TLC plate
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a small amount of inorganic binder is mixed in
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why does the TLC fluoresce under UV light?
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an inert inorganic material that fluoresces is mixed in with the adsorbent and binder
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why must we be careful with the silica gel and alumina used in TLC
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it is abrasive and can scratch your eyes
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the developing solvent used in TLC chamber
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50/50 mixture of ethyl acetate/hexanes
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Rf stands for
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retention factor or ratio of fronts
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what kind of melting point range indicates that the compound is impure
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a range greater than 2 degrees C
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why does the presence of impurities lower the melting temp
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it increases entropy and lowers the energy required to melt the compound
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eutectic point
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the lowest m.p. observed for any mixture of two components. it's a sharp melting point
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what's the H-C-H angle in methane (CH4)
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109 degrees
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how can you tell whether you have enough of your unknown on your tlc plate
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visualize with the uv lamp
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how many atoms will be attached to an sp-hybridized carbon atom
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2
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T or F, latex gloves are useful w/ organic chemicals
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false
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what can you deduce if your compound dissolves in sodium bicarbonate solution
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my compound is an acid
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which is the most efficient technique for removing suspended solid impurities prior to recrystallization
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hot vacuum filtration
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what was the name of the compound recrystallized in Recrystallization
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acetanilide
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molecular formula of sodium bicarbonate
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NaHCO3
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what is a disadvantage of recrystallization
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loss of product
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why is it important to place the recrystallization solution in an ice-water bath after it has reached room temp
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it will help to increase recovery of crystals
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the torsion angle is also called the
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dihedral angle
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what solvent is used to dissolve acetanilide
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water
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true or false? recrystallization is a good purification technique
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false
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what should you do if your solution oils out (Recrystallization)
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add more solvent to redissolve the oil
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when the dihedral angle between two groups is 180 degrees, what is the name of the conformation
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anti
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what will IR radiation not pass thru
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glass
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three advantages of Attenuated Total Reflectance (ATR) in IR
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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 |
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conformations of a molecule can be formed by . . .
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making and breaking of bonds
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in the Extraction experiment the final product is isolated as a solid/liquid/gas/ionic salt?
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solid
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the normally scanned range in cm-1 for IR is
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400-4000
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in Extraction, why would the phenol layer ever be on top of the water?
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if you have a lot of salts dissolved in the water and it becomes more dense than the phenol
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define a wavenumber
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the number of waves that fit in a certain distance
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is IR destructive or non-destructive
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non
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a c=o stretch can be found around...
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1700 cm-1
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the selection rule to observe an active IR band:
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change in dipole moment
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from which layer of an extraction using dichloromethane and aqueous sodium bicarbonate could benzoic acid be isolated?
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dichloromethane layer
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when comparing the relative amounts of two or more compounds eluted from a GC, one should compare...
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the peak area ratio
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a requirement of a molecule for it to be purified by distillation
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must be heat-stable
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three reasons dichloromethane was used as the organic solvent in Extraction
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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 |
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we need to inject ____ microliters of the sample mixture into the GC
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40
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in the TLC experiment, the solid sample is dissolved in . . .
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methanol
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simple distillation fails for compounds that are . . .
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non-volatile
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a GC column separates mixture based upon . . .
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compound-stationary phase interaction
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for TLC, the stationary phase is usually ____ and the mobile phase is usually _____
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polar, nonpolar
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bp of a liquid is the temp at which
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the vapor pressure equals the atmospheric pressure
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what feature of a GC would indicate a pure sample
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a single peak
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why do we seal the TLC jar
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to prevent the solvent from evaporating
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potassium permanganate reacts with . . .
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akenes and alkynes
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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 _____
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polarity
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what part of the spot do we measure for Rf value
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middle
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eugenol, a component of clove oil, has been widely used as ______
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a dental analgesic
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eugenol will be extracted from a dichloromethane solution by treating with ______ to make a water soluble salt
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NaOH
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aspirin, acetominophen, and ibuprofen are all part of a common class of pain relief agents called:
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analgesics
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_______ is a process that can be used for separating temp-sensitive natural products like limonene from citrus peels
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steam distillation
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why would phenol not be a good solvent for Phase Transfer
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it will react w/ the alyl bromide
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in extraction, what should you do if you observe an emulsion
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add more water
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which is a common phase transfer catalyst
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Benzyl tri-n-butylammonium chloride
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requirement for steam distillation
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material must be immiscible in water
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which are more constant, upper or lower mp range values
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upper
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darkening
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an obvious color change by the material in a capillary tube when heating
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