PAPER 2 Flashcards
what is the equation for the constant reforming and break dwn of ozone
what is the equation for the formation of chlorine free radicals from CFCs in the atmosphere
what are the equations for the depletion of ozone
what are the equations for the depletion of ozone by nitorgen oxide
why was the benzene model accepted over the kekule model
- x-ray evidence suggests that tghe length of the c-c bonds are all the same length, between the shot c=c and the longer c-c
- only reacts with bromine/decolourises it at high temp or with the presence of a halogen carrier
- enthapy of hydrogenation is less exothermic than expected for kekules (-360kj vs -208kj)
what are the electron withdrawing groups
NO2
COOH
3,5 directing
what are electron donating groups
OH
NH2
2,4,6 directing
formula for reaction of an aldehyde and tollens
aldehyde becomes a carboxylic acid and 2Ag and 2 H+
anahydride + alcohol
ester + carboxylic acid
NaOH + ester
salt (fromthe cooh) + alcohol
acyl chloride + alcohol
ester + HCl
whta is observedin many reactions with acylchlorides
white fumes of HCl
what is observed when forming primary amide
NH4Cl white smoke given off
acylchloride + phenol
ester + HCL fumes
amine + acid
ammonium salt (NH4+ (acid-)
ammonium salt + NaOH
convert back to amine
draw mechanism for ammonia/ethanol and haloalkane
nitrobenzene to aromatic amine
BLURT ALL
isoelectric point if R group is an amine
over 10
isoelectric point if R group is an carboxylic acid
below 3
how can peptide bonds be hydrolysed
acid or base
what words are used to describe optical isomers
- non-superimpossible mirror images
- ennantiomers
why do e/z isomers in a ring only have one isomer
- the ring is strained
- ring locks the groups on one side of the double bond
DONT SAY BC IT CANT ROTATR CUZ C=C CANNOT ROTATE ANYWAY
WHEN ASKED FOR TYPE OF POLYMER SAY
POLYAMIDE
POLYESTER
ADDITIONPOLYNER
WHEN ASKED FOR TYPE OF POLMERISATION
CONDENSATION
ADDITION
condensation with acylchlorides release what rather than H2O
HCl
why is it beneeficial to use acylchlorides rather than carboxylic acids in polmerisation
- higher yeild as reaction is not reversible and instead goes to completion
BUT it releases hazardous HCl fumes
what is a COOH group on a benzene going to do to reactivity
decrease as it it an e- withdrawing group
define sigma and pi bond
σ-bond: Overlap of orbitals between (bonding) atoms
π-bond: Sideways overlap of (adjacent) p-orbitals
developing agents for TLC
ninhydrin ( sprayed on)
UV light
why would two amino acids appear as one spot on TLC ???
- because they have very similar rf values similar affinities for either phase
- partially hydrolyseed or unhydrolysed
important feature of carrier gas in Gass chromatogpraphy
unreactive
inert
what is the mobile phase in gas chromatography
- inert gas e.g. helium
what is the stationary phase in gas chromatography
High BP liquich absorbed into a solid
porous support solid…
how are chemicals usually identified when then come out of gas chromatography
- mass spec
what would u use to hydrolyse a protein
CONCENTRATED HCL
how does a liquid stationary phase seperate a mixture
relative solubility
how does a solid staionary phase sperate mixture
adsorption
what are 2 solvents used in H NMR
CCl4 - non polar solvent
CDCl3 - polar solvent
what is used to calibrate H NMR ( and C)
TMS
tetramethylsilane
why is TMS used
- only 1 peak
- peak is far from others
- inert
- ## non-toxic
why is D2O used
to identify protons in O-H and N-H
what does chemical shift show
the relatice scale of how far frequency of protons signal shifted from TMS
why is ozone important
it basorbs / filters out harmful UV rays that can cause skin cancer in humans
what causes the ocnstant break down of ozone
uv light
what is a carboxylate ion
RCOO-
