Midterm Flashcards
Where are the two safety showers?
the two corners next to the wall with the door
Where are the two fire blankets?
above the supply cart and in the back corner next to the wall
Where is the eyewash station?
at the end of the second hood from the front
Where are the three fire extinguishers?
(you are facing the wall with the door) at the right of both hoods and in the left corner
Name the piece of equipment-> large open glass cylinder
beaker
Name the piece of equipment-> long thin open cylinder with a pentagon bottom and many measurement marks
graduated cylinder
Name the piece of equipment-> regular flask
Erlenmeyer flask
Name the piece of equipment-> large flask with side port
vacuum filter flask
Name the piece of equipment-> closed funnel with holes in it
Hirsch funnel
Name the piece of equipment-> metal rod with two flat, curved ends (like a scoop)
microspatula
Name the piece of equipment-> long glass rod with rubber tip
stirring rod with rubber policeman
Name the piece of equipment-> metal rod with bristles at the end
test tube brush
Name the piece of equipment-> metal grabbers that the metal curves out at the end
crucible tongs
Name the piece of equipment-> metal grabbers with two curved half cylinders at the end
test tube clamp
Name the piece of equipment-> like tweezers, but not
forceps
Name the piece of equipment-> pot with a stick on it
casserole
Name the piece of equipment-> fancy glass tube that is straight
air condenser
Name the piece of equipment-> fancy glass tube with two side ports and an extra middle layer
water-jacketed condenser
Name the piece of equipment-> long glass tube with a reservoir and funnel-like section at the end (like a vase on a stick)
thistle tube
Name the piece of equipment-> short glass tube with side port and a screw-on top
sublimation adapter
Name the piece of equipment-> glass tube with one end going into two (shaped like a y)
claisen adapter
Name the piece of equipment-> glass tube that narrows a lot and takes a hard right turn
drying tube
Name the piece of equipment-> glass tube with a little reservior thing (we used it to distill stuff)
hickman still head
Name the piece of equipment-> glass vial with a a triangle shaped bottom
conical vial
In the simple distillation lab, where should the thermometer be?
below the entrance to the collection chamber and not touching the side of the tube
What is the structure for 2-Butanone?
four carbons in a chain, the second is double bound to an oxygen
What is the structure for Ethyl Acetate?
four carbons in a chain, the middle two are single bonded to the same oxygen and the second one is double bound to an oxygen
What is the structure for Fluorene?
two benzene rings on either side of a cyclopentane
What is the structure for 2-Nitroaniline?
benzene ring with two side-by-side substituents
the first is an nh2 and the second is an positive n single bonded to one oxygen and double bound to another
What is the structure for Toluene?
benzene ring with a methyl
What is the structure for trans-1,2-dibenzoylethylene?
four carbons in a chain, ending with a benzene on each side
the end carbons are also double bound to oxygens, and the middle two carbons are double bound to each other
What is the structure for acetone?
three carbons in a chain, the middle carbon is double bonded to an oxygen
What is the structure for acetanilide?
benzene ring, bound to an nh, which is bound to a carbon that has a side double bond to an oxygen, and is also bound to another carbon
What is the structure for biphenyl?
two benzene rings attached with a line (no extra carbons)
What is the structure for benzophenone?
two benzene rings that are each bound the same carbon, which is also double bonded to an oxygen
What is the structure for benzhydrol?
two benzene rings that are each bound to the same carbon, which is also bound to an OH
What is the structure for petroleum ether?
six carbons in a chain
What is the structure for dichloromethane?
ch2cl2
What is the structure for hexane?
six carbons in a chain
What is the structure for methanol?
ch3oh
What is the structure for cyclohexane?
six carbons in a ring (he has it in a chair configuration with the extra hydrogens shown)
What is the structure for ethanol?
ch3ch2oh
What are the two main uses of melting points?
Identification and determination of purity
What is tare?
the mass of an empty container
What is the use of cotton plugs in a pasteur filter pipet?
to slow the liquid flow to prevent leakage and dripping
Can you measure the refractive index without a light-dark interferface?
yes, because we are using an Na-D line
What causes liquid to enter a capillary bell during a boiling point measurement?
the vapor cooling to the boiling point
When doing a gas chromatography, what problems would a low injector temperature cause?
it will produce a broad band that will make separation and quantification difficult
When doing a gas chromatography, what problems would a low detector temperature cause?
it could produce clogs
When doing a gas chromatography, how is retention time affected by injector temperature?
no effect
When doing a gas chromatography, how is retention time affected by column temperature?
it will lower the retention time of any compounds that have a lower BP than the temperature it is set at
When doing a gas chromatography, how is retention time affected by detector temperature?
no effect
When doing a gas chromatography, how is retention time affected by the size of the injected sample?
no effect
When doing a gas chromatography, how is retention time affected by detector attenuation?
no effect
When doing a gas chromatography, how is retention time affected by column length?
short columns give shorter retention times
How do you calculate percent error?
(Expected-Measured)/(Expected) * 100
How do you calculate percent recovery?
(amount of pure recovered)/(amount of crude used) * 100
What is the effect of impurities on melting point?
Lower it and increase the range (if soluble)
What is the effect of solute on solvent boiling point?
raise it
What is “eutectic”?
A homogenous mix that melts and solidifies at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.
What change is measured in a refractive index?
The change of the speed of light as it passes from the air into another medium, such as an organic liquid
What is a theoretical plate and what is its use?
A theoretical plate (N) is defined as one cycle of evaporation-condensation. A simple distillation has only one. The efficiency of fractional distillation is quantified by the number of theoretical plates, because multiple theoretical plates give better separations.
What is an “azeotrope”?
An azeotrope is a non-ideal binary liquid mixture. Low boiling azeotropes are more common. At the minimum or maximum BP azeotropic composition, the liquid and vapor have the same composition and cannot be separated by distillation. Changing the distillation pressure can move or eliminate the azeotrope.
Describe the technique used for determining the composition of distillate fractions
RI spectroscopy is used because toluene and cyclohexane have significantly different RI’s, and the RI of a solution made of both can be used to determine percent composition.
What are the two types of GC columns? Describe them.
Packed
made of tubing packed with small, uniform size, inert support coated with a thin film of nonvolatile liquid
Capillary
made of fused silica capillary tube coated in the interior wall with polymer
give better separations and can separate complex mixtures containing many compounds, but they require more sensitive detectors.
What are the two types of GC detectors? Describe them.
TC (thermal conductivity)
works with a packed column
the column gas flow cools a heated filament and the change in temperature causes a change in electrical resistance. The difference between that and the reference (only the gas) is used
FID (flame ionization detector)
works with a capillary column
the sample is burned in a H2 flame creating ions that cause the flame to conduct current, resulting in a signal
What is the effect of GC column temperature on separation and resolution?
The separation of peaks is determined by the column temperature: as it increases, the peaks elute more rapidly and separation decreases. At low column temperatures, compounds with lower boiling points spend more time in the mobile phase than those with higher boiling points, so they move faster and come off the column sooner. At high column temperatures, all compounds spend more time in the mobile phase, and all move faster.
What is the retention factor, Rf? How is it used?
Distance from starting line to center of sample/Distance from starting line to final solvent front (d/D). Rf can be used to identify unknown components.
What is the relationship between compound polarity and Rf?
Lower the polarity the higher the Rf. The stronger a compound is bound to the adsorbent, the slower it moves up the TLC plate.
What is the relationship between solvent/eluent polarity and Rf?
In general, the more polar the eluent, the more rapidly a given compound moves, and the higher the Rf. Polar compounds, which are strongly attracted to the absorbent, require polar eluents to attract them away from the adsorbent. Solvent polarity should be arranged so that it spreads compounds across plate.
Describe common spot visualization methods.
Visualization is the detection of the spot on the plate when it is not not colored. The two most common methods are UV and I2 vapors. In UV , a fluorescent dye is present on the plate and the compound spots quench fluorescence and show up as a dark spot on a glowing plate. In the I2 method, the plate is placed in a container of I2 so that the vapors absorb on the spots and produce purple spots. A third technique is to spray visualization reagents on the plates, which will develop colors with specific types of compounds.
What are the four solvent selection criteria for a recrystalllization?
The compound being purified must be insoluble in the solvent at RT.
The compound should be soluble in boiling solvent.
The solvent BP must be lower than the compound MP.
Abundant crystals should be recoverable from cool solvent.
What is ‘oiling out”?
If the compound is above its MP when it begins to seperate from solution, it forms a molten “oil” phase rather than crystals. The ‘oil’ frequently refuses to form crystals after cooling to RT or ice bath, due to trapped solvent. However, a seed crystal of the pure compound sometimes initiates crystallization.
