Organic Lab Practical

Are you an organic lab menace?

Question 1:Pure benzophenone melts at 48-49 deg. Celsius. What effect on the melting point would a trace of naphthalene have (naphthalene melts at 80-82 deg. C)
it would raise the mp
it would have no effect
it would lower the mp

Question 2:What effect would a grain of sand have on the benzophenone mentioned in question 1?
it would raise the mp
it would have no effect
it would lower the mp

Question 3:a. Is water or ligroin better for recrystallizing benzoic acid (PhCOOH)? b. Is water or ligroin better for recrystallizing stilbene (PhC=CPh)?
a. ligroin b. water
a. ligroin b. ligroin
a. water b. ligroin
a. water b. water
a. water b. ligroin

Question 4:Which of the following is done first in the recrystallization procedure?
decolorize the solution
choose a suitable solvent
dry the product
induce crystallization by cooling and/or scratching
filter the product

Question 5:You are given a sample that is slightly impure. When you determine the melting point, it melts at 51-55 deg. C. You are told that the compound is either benzophenone (mp 49-51 deg. C), maleic anhydride (mp 54-56 deg. C), 2-nitroaniline (mp 71-73 deg. C), or naphthalene (mp 80-82 deg. C). Which do you think it is?
maleic anhydride
it cannot possibly be any of these choices!!!!!

Question 6:Ethers react with a._______ in the air to form b.________.
a. oxygen b. explosive trinitrotoluene
a. nitrogen b. flammable nitroethers
a. oxygen b. explosive peroxides
a. hydrogen b. fire
a. ozone b. a violent reaction

Question 7:After performing a recrystallization, where are the impurities found after the recrystallization?
in the filter paper
they evaporate
on the surface of the pure crystals
in the filtrate
they are converted to innocuous materials

Question 8:What is a common stationary phase in column chromatographY?
iron (III) chloride
magnesium oxide
sodium sulfate
potassium carbonate

Question 9:In normal column chromatography, what would you do to shift the equilibrium from the solid stationary phase to the liquid mobile phase?
use more polar mobile phase
use less polar mobile phase
increase the amount of mobile phase
reduce the amount of stationary phase
it cannot be done

Question 10:What is the most common mobile phase in gas chromatography?
carbon tetrachloride

Question 11:Which of the following analytical techniques measures the energy of electronic excitation by 200-800 nm light and is also used to infer conjugation and quantify amounts of a compound?
mass spec

Question 12:Which of the following is a bad idea during column chromatography?
dissolve the sample of interest in the minimum of solvent before applying to the column
make a slurry of alumina and solvent to load into the column
allow the mobile phase to go 1 inch below the top of the column before adding your sample
put a layer of sand on top of the column
collect small fractions (within reason)

Question 13:Simple distillation is more useful when the compounds boiling points are:
more than 5 degrees apart
more than 25 degrees apart
more than 45 degrees apart
more than 75 degrees apart
more than 200 degrees apart

Question 14:Methanol boils at 65 deg. C and 1-butanol boils at 117 deg. C. How would you separate them?
fractional distillation
simple distillation
liquid-liquid extraction

Question 15:What would you use to extract benzoic acid from a mixture of phenol, aniline, and methoxybenzene in dichloromethane?
NaHCO3 (aq)
NaOH (aq)
HCl (aq)

Question 16:After accomplishing the goal of question 15, how would you extract the phenol?
NaOH (aq)
NaHCO3 (aq)
HCl (aq)

Question 17:How would you extract the aniline
NaHCO3 (aq)
NaOH (aq)
HCl (aq)

Question 18:Which of the following is not applicable to thin layer chromatography?
mobile phase
triple point
solvent front

Question 19:How are TLC spots typically visualized?
IR glasses
UV light
I.O.N. chamber
silver nitrate bath

Question 20:Rf is calculated by:
distance solvent travels - distance spot travels
distance solvent travels + distance spot travels
product of distance spot travels and distance solvent travels
distance spot travels divided by TLC factor (from table)
distance spot travels/distance solvent travels

Question 21:Arange the following in order of increasing Rf in TLC: octanoic acid, decane, 1-pentanol
decane, 1-pentanol, octanoic acid
1-pentanol, decane, octanoic acid
decane, octanoic acid, 1-pentanol
octanoic acid, 1-pentanol, decane
octanoic acid, decane, 1-pentanol

Question 22:The nitrogen rule is commonly applied in:
mass spectroscopy

Question 23:GC can be used to quantify relative amounts of organic compounds after accounting for:
molecular weights
extent of conjugation
relative response factors
boiling points
vapor pressures

Question 24:The boiling points of water and 2-methyl-2-propanol are 100 deg. C and 82.2 deg. C, respectively. Which has the lower vapor pressure at room temperature?
both have the same vapor pressure at room temperature

Question 25:Which is not a commonly used drying agent?
sodium sulfate
magnesium sulfate
cesium fluoride
calcium chloride

Question 26:Sublimation is
passing from the liquid to solid phase
passing from the liquid to gas phase
passing from the gas to solid phase
condensing into the liquid phase
passing from the solid to gas phase

Question 27:How can you tell which layer is which during a liquid/liquid extraction?
smell them
flame test
density usually works
silver spatula test
Tollen's test

Question 28:What is the purpose of the packing in fractional distillation?
provides insulation for the rising vapors
cools the vapors for collection in the still pot
prevents flashback and flooding
provides theoretical plates for multiple distillations
they provide tensile strength

Question 29:p-dichlorobenzene boils at 54-56 deg. C; cyclohexane boils at 80.7 deg. C; which will elute from a GC column first?
neither - liquids aren't used in GAS chromatraphy!!!! (wink)

Question 30:You have a sample that is known to be either benzophenone (has a carbonyl plus aromatics) or naphthalene (only aromatics). What is a quick, easy, spectroscopic way to find out?
mass spec
refractive index

This Quiz has been designed by David Flosser.