organic chemistry Flashcards
define a fuel
a substance that burns in air or oxygen to release a usable amount of energy
define functional group
an atom of group of atoms in an organic molecule that largely determine the molecules properties and reactions
define hydrocarbon
a compound that contains only carbon and hydrogen
define homologous series
a series of compounds with similar chemical properties and the same general formula, in which each member contains on CH2 unit more than the previous number
define structural isomer
a compound that has the same molecular formula, but a different structural formula
incomplete combustion
occurs when supply of air/oxygen is insufficient, so CO2 not produced. water and carbon, or carbon monoxide and water are produced
complete combustion
requires plentiful supply of air so that elements in fuel can fully react w excess oxygen. produce CO2 and water
alkanes
a saturated hydrocarbon containing only single bonds between carbon atoms. general formula CnH2n+2
X decolourise bromine water
reacts in UV light
tetrahedral geometry - bond angle of 109.5 deg
alkenes
an unsaturated hydrocarbon, containing one or more double bonds present between carbon atoms. general formula CnH2n
decolourises Br water from orange -> colourless
planar geometry - bond angle of 120 deg
carboxylic acids
name ends in -oic acid
carbon in carboxyl functional group -COOH, is carbon no 1 in parent chain
alcohols
name ends in -anol
contains one hydroxyl -OH grp on chain
primary, sec, tert alcohols
primary = carbon w -OH is bonded to no or 1 carbon atom and oxidise to carboxylic acids
secondary = carbon bonded to 2 and oxidise to form ketones
tertiary = carbon bonded to 3 other
alkynes
unsaturated hydrocarbon, containing one or more triple bond present between carbon atoms. general formula CnH2n-2
decolourises bromine water
linear geom - bond angles 180 deg
amines
replace last -e of alkane w -amine
primary amines have structure alkyl group-NH2 (func grp)
amino- prefix w higher func grp
amides
contain -CONH2 grp always on carbon 1 of parent chain
suffix -amide and prefix amido-
aldehydes
have the C=O bond at start of parent chain
contains -CHO functional group
name = add -al onto corresponding alkane
H-C=O
ketones
contain a carbonyl group, C=O
can be anywhere in chain
alkane ending with -one eg. alkanone
priority in naming
carboxylic acid
ester
amide
aldehyde
ketone
alcohol
amine
alkene
alkyne
alkane
haloalkane
branches
esters
contain ester func group =OCO-
formed from reaction of carboxylic acid and an alcohol
alkyl group (off the single oxygen) - yl hydrocarbon chain attaching to -COO, oate
uses of ethanol
solvent in perfumes, inks and glues
fuel to make biofuel
to make ester, used in food flav.
alcoholic drinks
prod of ethanol from fermentation of glucose
biological method
glucose -(yeast catalyst)-> ethanol + carbon dioxide
cheaper, sugar from sugar cane=renewable BUT slow, batch process and impure ethanol produced
prod of ethanol from hydration
chemical method
ethene + steam -> ethanol
fast, continuous, pure ethanol produced BUT expensive, uses ethene from crude oil = non renewable
addition polymerisation
alkene molecules = monomers
under pressure and with a catalyst, double bond b/w monomers breaks and bonds form to form poly____
define monomer
molecule that can be bonded to other identical molecules to form a polymer
substitution reaction
alkanes = saturated so undergo limited chemical reactions
alkane + halogen -(UV light)-» haloalkane + hydrogen halide
producing alcohol from haloalkane
haloalkane + OH- -> alcohol + halide ion via sodium or potassium hydroxide solution
addition reactions of alkenes
alkene + hydrogen halide -> haloalkane
alkene + hydrogen -> alkane (need nickel catalyst and 150 deg for HYDROGENATION)
alkene + water -> alkanol (need phosphoric acid catalyst, 300 deg, 60-70 atm for HYDRATION)
formation of esters
reversible reaction
reaction b/w alkanol and acid
condensation reaction = produce h2o
esterification reaction
need H2SO4 catalyst
oxidation of prim and sec alcohols
primary: oxid by acidified permanganate (H+/MnO4-) or dichromate solution (H+/Cr2O72-) to produce aldehydes and carboxylic acids
eg. ethanol -> ethanal -> ethanoic acid
sec: oxid by same oxidising agents to form ketone (C=O)
bonding b/w alkanes based w dispersion forces
-molecules can be closer to one another, can pack more closely depending on shape
-larger molecules have more regions of charge to attract each other
-disp forces strength = increased
solubility of organic molecules in water
small alcohols, amines, aldehydes, ketones, carboxylic acids, amides = able to form H bonds w water so soluble
water dissolves organic molecules by forming dipole-dipole attraction and H bonds w them
elastomers
type of polymer
can be stretched or deformed
can regain their shape
only a few cross links = sulfur bridges
thermosetting
type of polymer
cross links b/w chains
much higher melting points
cannot be remoulded
rigid and inflexible
eg. used on kitchen bench covering
thermoplastic aka thermosoftening
type of low density polymer
chains loosely tangles together
no cross links
low melting point
can be remoulded
eg. plastic bags, cling wrap
LDPE
low density polyethene
formed under high temps and pressure
branched chains = X fit together well so amorphous
low MP
soft and flexible
HDPE
high density poly ethene
formed using catalyst at low temp + pressure
unbranched chains
fit together much better, more crystalline, less amorphous
form harder substance eg. wheelie bins, classroom chairs
