CHE 231 Lab Review Flashcards

Terms Definitions
recrystallization is used to ____ a substance
purify
The solute should have a ___ solubility in the hot solvent and ___ solubility in the cold solvent.
maximum, minimum
_____ chemicals recrystallized from nonpolar solvents
nonpolar
The boiling point of the solvent will be ___ than the melting point of the solute
lower
__________ is used to remove colored impurities from recrystallization.
activated charcoal
To start crystal formation, you may _____ the solution
seed
Impurities ___ melting point
lower
When a solid turns directly into a gas, ignoring the liquid phase
sublimation
What chemical is used in the old-fashioned IR pellets?
KBr
boiling point of water?
100 degrees celsius
Dilstillation
technique used for seperating a misture of liquids
Boiling point and vapor pressure are inversely proportional, meaning
the higher the BP, the lower the vapor pressure and vice versa
69°C
BP of hexane
111°C
BP of toluene
between 30-40°C
An effective distillation requires that the components of the solution have significatly different BP's, like
theoretical plate
represents one vaporization/condensation cycle
phase diagram
has mole fraction of hexane by toluene
Fractions picked up in what equipment?
Hickman still head
When packing compounds hexane/toluene, pack with
parafilm, aluminum foil
Explain Gas Chromatography
Seperation is based on partitioning of a mixture between a stationary phase and a mobile phase
Explain Stationary phase
high BP liquid which is supported on an inert solid support in the column. (all in oven)
Mobile phase in fractional distillation
carrier gas which is passed through column (He)
retention time in GC
Amoint of time a component interacts with the stationary phase (lower BP = lower retention time)
Waste of fractional distillation
organic hazardous liquid waste container
Solvent extration used to
seperate a mixture with an acidic, basic, and neutral compoind by liquid-liquid extraction (based on solubility)
How to test purity of solvent extraction
test MP of solids extracted by lit. value
Two methods of solvent extraction?
solid-liquid, liquid-liquid
partition coefficient
When a compound is placed in two solvents that wont dissolve in each other, so it dissolves in the one its more soluble in
bronsted acid
proton donor
bronsted base
proton acceptor
lewis acid
electron pair acceptor
lewis base
electron pair donor
Compounds used in solvent extraction
benzoic acid, ethyl 4-amino benzoate, 9-flourenone
Na2SO4
Compound used to dry neutral in solvent extraction
metal hydrides used to
reduce
cyclohexanone, sodium borohydride, methanol =
cyclohexanol
We don't reduce with LiAlH4 because..
it generates hydrogen gas
NaBH4 only reduces
aldehydes and ketones
nucleophile
nucleus seeking
electrophile
electron-seeking
In TLC, mobile phase is a ___, stationary phase is a
liquid, solid (silica gel)
Rf
distance traveled by solute (from origin)/ distance traveled by the solvent front (from origin)
The more polar moves spots ______ the plate
further up
From lowest to highest on TLC plate (polar, basic, nonpolar)
basic, polar, nonpolar
Solve: big blotchy spots
Use less sample
Solve: no spots visible
not enough sample, or solvent too high, or compound was washed off
Solve: spot is a streak
compound not soluble enough or solvent is naturally perverse
propyl p-tolyl ether
What did we make in williamson synthesis?
What was the phase transfer catalyst in williamson synthesis?
tetrabutyl ammonium bromide
Going around left to name a compound with p,m,o, its:
omp, with p across from the group.
Phenols are (acidic, basic)?
acidic due to aromatic ring
Williamson ether syntehsis is sn1/2?
sn2
Tetrabutyl ammonium bromide carries what into organic layer?
p-cresol anion
Williamson synthesis reaction occurs at what temp?
110 degrees C
Organic layer of Williamson synthesis?
propyl-p-tolyl ether, phenol and salts
Nonorganic layer of Wil, synth?
salts, Na+I-, NaOH
Dried stuff in Will synth with? Remove impurities with?
Na2SO4, SiO2
Benzoin ->
Benzil
Benzaldehyde ->
Benzoin
Cyanide attacks molecule of benzaldehyde and then..
carbon of that benzaldehyde attacks the other carbon of the other benzaldehyde
O-H appears at what in IR?
3500-3200
Sp2 C-H appears at what in IR?
3100-3000
Sp3 C-H appears at what in IR?
3000-2850
C=O appears at what in IR?
1700
benzoin waste in what container?
Cyanide, solid or liquid
Benzoin should be at what range in MP?
142-145 degrees C
In oxidizing reactionsm oxidizing metals will be
reduced
What gas is produced in the benzil reaction?
Nitrogen
MP of benzoin
95-96
Step 1 has what chemical and what reaction?
Tetraphenylcyclopentadienone in an aldol condensation reaction
Step 2 has what chemical and what reaction?
stilbene Dibromide and an electrophilic addition reaction
Step 3 results in what chemical and what reaction?
diphenylacetlene and a double elimination reaction
Step 4 results in what chemical and what reaction?
hexaphenylbenzene and a diels-alder reaction
luminol is also called
3-aminophthalhydrazide
Two chemicals to make luminol?
3-nitrophthalic acid and hydrazine
cyalume is a (ether, ester?)
ester
Chemiluminescence reaction
A chemical reaction during which there is an emission of light.
Waste goes in what place for luminol
luminol experiment: synthesis waste
Benzil waste goes in
soda lime waste container
Fractional distillation wate goes in
organic waste container
solvent extraction wash layer goes in
aqueous waste for acids and bases
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Term:
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