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35 Cards in this Set
- Front
- Back
definition of melting point |
when solid is in equilibrium with liquid phase |
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eutectic temp |
actual lower limit of melting point range |
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when looking on graph of melting point and boiling point |
flat section between mp and bp is due to extra heat breaking intermolecular forces so there is not rise in temp |
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how to tell if compound is pure from mp |
if the range is less than 2 |
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extraction |
transfer of a solute from one phase to another ex. coffee powder and hot water = black coffee 2 types: solid liquid liquid liquid |
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polar bond |
if two atoms have different electronegativities and are bonded to each other, the bond is said to be polar |
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know polarity of commonly used solvents |
water most polar |
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recrystallization |
purification of an impure organic solid |
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choice of solvent |
solute should be insoluble in room temperature solvent should be soluble in heated solvent should crystallize when put in ice following heating **solvent should have low bp |
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types of impurities |
insoluble colored soluble |
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for insoluble impurities |
dissolve in solvent and filter off impurities |
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for colored impurities |
use norite and then do hot filtration, why hot? |
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for soluble impurities |
recrystallization, dissolve in solvent then let pure compound recrystallize and leave the impurities in mother liquor |
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why do impurities not crystallize out? |
starting material is mostly the compound we are looking for solution is concentrated with respect to the desired material but dilute with respect to the impurities as solvent cools and starts to evaporate, the solution becomes more concentrated in the desired compound and crystals start to form |
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chromatography |
separation of two or more compounds one is in still phase, one is in moving phase diff compounds will have diff solubilities and thus diff absorptions in the two phases |
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adsorption chromatography |
distribution of solutes between a moving solvent and a solid adsorbent |
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uses of tlc |
to determine the number of components in a mixture to determine the identity of substances to monitor the progress of a reaction to determine the effectiveness of purification to determine the conditons for column chromatography to monitor column chromatography |
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method for tlc |
solvent moves up plate by capillary action three interactions on tlc plate solvent and adsorbent solvent and compound adsorbent and compound ions have highest interaction with adsorbent |
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liquid liquid extraction |
a solution containing several components is mixed with a second immiscible solvent in order to extract some components into that second solvent ex. water and oil |
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immiscible |
does not mix to form a homogenous solution or does not dissolve in first solvent |
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what happens in mixture of water and organic solvent? |
water: polar organic: most organic compounds are not very polar so they are not soluble with in water but are soluble in organic solvent |
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distribution coefficient k for c |
depends upon solubility of C in both solvents k=concentration of C in S1/ concentration of C in S2 |
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when organic compound is mixed with water |
very little will go into the aqueous layer so not useful need to do acid base chemistry |
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organic acids and bases used in lab |
carboxylic acid RCOOH phenol(aromatic ring) ArOH(weakest) sulfonic acid RSO3H(strongest) amines; primary amines- RNH2 secondary amines-RR'NH tertiary amines- RR'R"N anilines- ArNH2 |
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organic layer must be dried |
1. extraction by saturated sodium chloride solution(brine) 2. anhydrous drying agent such as sodium sulfate |
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boiling point |
defined as the temp at which the vapor pressure equals atmospheric pressure |
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applying increasing amounts of heat to a boiling liquid |
will not increase the temp but will cause molecules to move from the liquid to the gas phase more quickly |
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distillation |
the vapor above the mixture is richer in the lower boiling point compound so a series of distillations would create a pure distillate |
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c=0 |
1670-1820 |
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c=c stretch |
1400-1600 |
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c=c-h stretch |
3000 |
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oh |
3200-3600 |
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functional group transformation |
a reaction that changes the functional groups but not the carbon backbone |
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reduction |
converts ketone to secondary alcohol use complex metal hydrides |
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oxidation |
converts secondary alcohol to ketone |