ochem lab 3 Flashcards
(24 cards)
compounds used in the experiment
acetaminophen, aspirin, caffeine
development solvent
10% hexane in ethyl acetate
solvent mixed with pill
50% methylene chloride in ethanol
Rf value
distance travelled/distance of solvent front
tlc basis
polarity between sample and stationary+mobile phase
mobile phase
methylene chloride or methanol (organic solvent)
sample to be separated is first
adsorbed onto surface of solid through polar interaction
mole polar samples adhere more or less
more
what does mobile phase do
sweeps across stationary phase, competing for sample.
elution
process by which solvent carries sample with it. solvent used for this process is the eluting solvent
more polar solvent does what
carries components of mixture with it better
more polar component travels
slower
common solid adsorbents
silica and alumina
common eluting solvents
methylene chloride, ethyl acetate, ethanol
solution of sample is applied on
solid support using a capillary tube using spotting
how far from bottom of tlc plate should mark be made
1 cm
how many applications of same solution
3-4
can different samples touch eachother?
no, min distance of 0.5 cm
eluting solvent/development solvent
10% hexane in ethyl acetate
when to stop tlc
1-2 cm from top
spot with highest rf value
least polar
are rf values reproducible
no must be on same plate at same time
tailing occurs with
highly polar substances
solution to little moving
increase solvent polarity
