organic analysis
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what is the functional group test and positive result for alkenes?
add bromine water turns from orange to colourless
what is the test for ALL alcohols and the positive result?
add sodium bubbles of hydrogen gas formed
what is the test which can help distinguish a primary/secondary alcohol from a tertiary one and what is the result?
warm with acidified potassium dichromate orange to green colour change for primary or secondary no change for tertiary
what are the two functional group tests for aldehydes and what are the positive results?
warm with tollens- silver mirror forms warm with Fehling’s solution- brick red ppt forms
what is the functional group test for carboxylic acids?
add sodium carbonate and effervescence due to CO2
what is the functional group test for the halogens and positive results?
add acidified silver nitrate and warm precipitates form chlorine; white and dissolves in dilute ammonia bromine; cream and dissolves in conc ammonia iodine; yellow and insoluble in dilute and conc ammonia
what can mass spectrometry be used to find?
the relative molecular mass of a compound
what is formed in a mass spectrometer?
a molecular ion is formed when a molecule an electron the molecular ion peak on the mass spectrum of the compound for any compound, the mass/charge (m/z) value of the molecular ion peak will be the same as the molecular mass of compound
what isotopes can affect the mass detected in mass spec?
isotopes of C13 and H2
where does fragmentation occur in mass spec? what is it?
for electron impact, is when covalent bonds in the molecular ion breaks then molecular ion breaks down to produce ions with a smaller m/z
what are high resolution mass spectrometers?
some mass spectrometers can measure atomic and molecular masses extremely accurately measures molecular mass and atomic mass to 4 dp
when is high res mass spec useful?
when compounds have the same rounded Mr but not when molecular formulas are identical
what is absorbed by certain groups in a molecule?
infra-red radiation at characteristic frequencies complicated spectra can be obtained that provide information about types of bonds present in a molecule
what do the peaks look like for O-H in alcohol and carboxylic acids, and C double bond O in ketones, aldehydes and acids?
O-H in alcohols; broad O-H in carboxylic acids ; very broad C double bond O in ketones, aldehydes, acids; strong and sharp
what is the area below 1500 using infrared spec for?
the finger printing region unique to a particular compound a computer will compare the IR spectra of the fingerprinting region to a data base of known pure compounds to identify the compound
what is the link between greenhouse gases and infrared?
3 main greenhouse gases; carbon dioxide, water vapour, methane they can absorb IR because they contain covalent bonds that can absorb IR
what is meant by the molecular ion in mass spec?
ion with m/z equal to Mr of molecule OR molecule with electron knocked off