Analysis
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- Created by: vickieboadi
- Created on: 28-01-21 09:48
what do all forms of chromatography have
they have a mobile phase and a stationary phase
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what does TLC stand for
it stands for thin layer chromatography
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what is thin layer chromatography
it is a quick and inexpensive analytical technique that indicates how many components are in a mixture. it uses a TLC plat with silica as the adsorbent substance as the stationary phase
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what is adsorption
is the process by which the solid silica holds the different substances in the mixture to its surface
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how do you carry out TLC
take out TLC plate use a pencil, dray a line about 1 cm3 from end of plate
using a capillary tube, spot a small amount of a solution of the sample onto the base line on the plate
prepare a chromatography tank for the TLC plate using a small beaker
using a capillary tube, spot a small amount of a solution of the sample onto the base line on the plate
prepare a chromatography tank for the TLC plate using a small beaker
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how do you carry out TLC (2)
with a watch glass at tome and pour solvent with 0.5 cm3 depth
put the TLC plate in the beaker and cover the beaker and wait for the solvent to rise up then circle any visible spots and draw a line where the solvent stops and if not then use UV lamp
put the TLC plate in the beaker and cover the beaker and wait for the solvent to rise up then circle any visible spots and draw a line where the solvent stops and if not then use UV lamp
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what is the equation for the Rf value
distance moved by the component / distance moved by the solvent front
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what is the stationary and mobile phase for gas chromatography
stationary is high boiling liquid and the mobile phase is an inert carrier gas
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how do you carry out gas chromatography
small amount volatile mixture injected into gas chromatogram. mobile phase carrier gas carries the component through capillary column which contain liquid stationary phase absorbed onto the solid support
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how do you carry out gas chromatography
the components slow down as they interact with the liquid stationary phase inside the column the more soluble components move slower in the capillary this is how they are separated
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what is the retention time
its the time take for each component to travel through the column
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what two pieces of information can be obtained by the gas chromatogram
retention times to identify the components present in the sample and peak integration to determine the concentration
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how do you find out the concentration of components
peak integrations - prepare standard solution, obtain gas chromatogram for each standard solution , plot a calibration curve peak area against conc. obtain gas chromatogram for compound investigated use calibration curve to measure conc.
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test for alkenes
add bromine water and the bromine water should decolourise from orange to colourless
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test for haloalkanes
add silver nitreate and ethanol and warm to 50 degrees Celsius.
chloralkane - white ppt
bromoalkane - cream ppt
iodoalkane - yellow ppt
chloralkane - white ppt
bromoalkane - cream ppt
iodoalkane - yellow ppt
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test for carbonyls
add 2,4 DNP and orange ppt should form
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test for aldehydes
add tolents'reagent and warm and a silver mirror should form
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what is the test for primary and secondary alcohols and aldehydes
add acidified potassium dichromate and warm in a bath and should go from orange to green
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test for carboxylic acids
add aqueous sodium carbonate and effervescence should be see
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what does NMR
nuclear magnetic resonance
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what is NMR spectroscopy
the technique used a combination of a very strong magnetic field and radio frequency radiation with the right magnetic field strength and frequency the nuclei of some atom absorb this radiation
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what is nuclear spin
it is the spin of the nucleus due to and odd number of nucleons
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what are nucleons
they are a term used to say protons and neutrons
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what is resonance
nucleus has two different spin states like electrons and with the a strong magnetic field and right frequency they can flip between the two different spin states
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how does it work
the frequency required for the resonance is proportional to the magnetic field and the strong-super conducting electromagnet is used, cooled to 4k by liquid helium
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how are NMR used in medicine
they are used as MRI body scanners and uses the same technique as NMR
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what is the frequency shift measured on
it is measured on a scale called chemical shift
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what are the units for chemical shift
pm - parts per million
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what is used as a standard reference
TMS it is given a chemical shift of 0 ppm
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what is the amount of chemical shift determined by
by the chemical environment especially if there is electronegative atoms
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what is used as a solvent for NMR spectra
deuteriated trichloromethan, CDCl3 produces a peak but filters out before peak is displayed on spectrum
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what info on the molecule does carbon-13 NMR show us
the number of different environments and the type of carbon environments present
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carbons on the NMR spectrum
carbons bonded to different atoms have different environments so absorb at different chemical shifts if there two C positioned symmetrically they are equivalent and have the same chemical shift
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what info does proton NMR show us
the number of different environments and the type of carbon environments present
and the relative number of each type of proton and they no. of non-equivalent protons adjacent to a given proton form splitting pattern
and the relative number of each type of proton and they no. of non-equivalent protons adjacent to a given proton form splitting pattern
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why can proton NMR peaks be split into sub-peas or splitting patterns
proton spins can interact with spin state of nearby protons that are in different environments
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Other cards in this set
Card 2
Front
what does TLC stand for
Back
it stands for thin layer chromatography
Card 3
Front
what is thin layer chromatography
Back
Card 4
Front
what is adsorption
Back
Card 5
Front
how do you carry out TLC
Back
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