organic chemistry real Flashcards
what is a hydrocarbon
compound formed with only hydrogen and carbon atoms
gen formula for alkane
Cn H2n
2 features of all alkanes
saturated compounds-each carbon atom forms 4 single covalent bonds
-a homologous series-organic compounds that react similarly
viscosity as hydrocarbon(gloopiness) gets longer
increases
volatility(how easily turns to gas) as hydrocarbon gets longer
decreases
flammability as hydrocarbon gets longer
decreases
bp and mp as hydrocarbon gets longer
increases
why are hydrocarbons used as fuels
it releases lots of energy when completely combusted
what are shorter hydrocarbons with lower bp used for eg
as bottled gases under pressure as liquids in bottles
what is the equation for complete combustion of hydrocarbons
hydrocarbon+oxygen—–>co2 +water vapour
what is crude oil
a fossil fuel formed from remains of plants and animals mainly plankton made of mainly hc(alkanes)
how was crude oil formed
high temps/pressure on remains that died millions of years ago buried under mud turns them to crude oil
how is crude oil extracted
drilled up from rocks
what are cons of fossil fuels like crude oil
take long to make so used faster than made meaning they are finite
what is fractional distillation
the way compounds in crude oil are seperated
1st step of fractional distillation
oil heated until most turns to gas and liquid is drained off
describe the temp conditions of the fractionating column
hot at bottom
cool at top
2nd step of fractional distillation
gases enter fractionating column
what happens to longer hydrocarbons in fractional distillation
condense back to liquids and drain out near bottom
what happens to shorter hydrocarbons in fractional distillation
condense and drain out at top where its cooler
what are you left with at the end of fractional distillation
crude oil mixture is seperated into diff fractions with mixture of hc with similar bp and no of carbons
why do longer hc and shorter condense at different fractions
They condense at regions lower than their boiling points
what hc condense at the top in fractional distillation
lpg
what hc condense in the middle in fractional distillation
petrol
kerosene
diesel oil
what hc condense at the bottom in fractional distillation
heavy fuel oil which can be
heating,fuel or lubricating oil
what is a petrochemical
A petrochemical is a substance made from crude oil, via chemical reactions.
what is a feedstock
A feedstock is a raw material used to provide reactants for an industrial reaction
what does the petrochemical industry use hydrocarbons from crude oil for
feedstock for new compounds like polymers
solvents
lubricants
detergents
what are organic compounds
compounds containing carbon
why do you have so many products from crude oil
carbon atoms bond to form different groups called homologous series
what is cracking
splitting of less useful high supply long chain hc from frac distillation to more useful shorter hc
what does cracking produce
alkane +alkene
what are uses of alkenes
starting materials for other compounds
polymers
what type of reaction is cracking and what are the types
thermal decomposition
-steam and catalytic
1st 2 Steps for catalytic cracking
heat long chain hc to gas
pass vapour across hot powdered aluminium oxide catalyst
step 3 and 4 of catalytic cracking
long chain molecules split
on surface of catalyst powder as specks
Describe process of steam cracking
vapourise hc
mix these with steam
heat to a high temp
why are alkenes called unsaturated
they have same no of carbons and 2 fewer hydrogens due to double bond
what is the functional group of alkenes
C=C
why are alkenes more reactive than alkenes
the double bond can open to be a single bond so carbons can bond to other atoms
alkene combustion compared to alkane
is the same
products are water and co2
what may cause alkenes to undergo incomplete combustion
burning in air
equation for incomplete combustion of alkenes
alkene+oxygen —>carbon +carbon mooxode+carbon dioxide +water
what are the results of incomplete combustion of alkenes
-smoky yellow flame
-less energy released than complete
what is a functional group
group of atoms in a molecule that determine how it will react
how do alkenes mostly react
via addition reactions
where carbon double bond is opened to leave single bond and and new atom added to each carbon
what happens when alkenes are hydrogenated
forms saturated alkane in the presence of a catalyst(eg platinum or nickel)
what are the alkene addition reactions
hydrogen
halogens-specifically bromine
steam
alkene reaction with halogen and eg
c=c bond splits to bond with halogen atom
and produces saturated molecule
eg
ethene +bromine—->dibromoethane
bromine water reaction with alkane vs alkene
-stays orange with alkane/saturated compound
-goes colourless when alkene is added
alkene reaction with steam
water is added across double bond(which split to be single bonds) and alcohol formed
+eg of alkene reaction with steam
ethene+steam
and then passing it over phosphoric acid catalyst+high temps/pressure
——–>ethanol
what happens after ethanol is formed in alkene+steam
mixture passed from reactor to condenser where ethanol and water condense(higher bp) leaving unreacted ethene gas
what is ethene addition reaction with steam a way of
-a way of industrially making ethanol
what happens with unreacted ethene gas in it and the alcohol in ethene+steam
-recycled back into reactor
-purified from mixture by fractional distillation
what is polymerisation
monnomers joining together to form long molecules called polymers
- addition often needs high pressure and catalyst
eg of a polymer and its monomer
what what it is based from
plastics
monomers are alkenes
usually carbon based
what are the monomers that make up addition polymers
unsaturated
how do unsaturated monomer molecules perform addition polymerisation
they open up double bonds and join to form polymer chains
for addition polymerisation what is the difference in displayed formulas between polymers and monomers
polymers have no double bond
monomers have
what is the functional group of carboxylic acids and what do they end with
-COOH
end with anoic acid
describe the structure of carboxylic acids func group
c is diagonally double bonded to o at the top
the same c is single bonded to oh at the bottom
it is always furthest right
what do carboxylic acids react the same as but what is the difference
acids
-form salts ending in anoate
eg sodium ethanoate
what type of acids are carboxylic acids and why
weak
when they dissolve in water they ionise/release h+ ions but incompletely so they are less acidic than strong acids of same con
what is the functional group of esters
-coo
what make up esters
alcohol and carboxylic acids
what catalyst is used in esterification
concentrated sulfuric acid
what is the reaction to form esters
alcohol+carboxylic acid—–>ester +water
conc sulfuric acid catalyst
ethanoic acid +ethanol forms
ethyl ethanoate
what would you see when sodium carbonate is added to aq solution of methanoic acid
effervessence as co2 gas is given off
what does condensation polymerisation involve
involves monomers with different functional groups joining to form a polymer and small molecule
what happens in condensation polymerisation involving small molecules
monomers react and form bonds forming polymer chains
every bond formed releases small molecule
(eg water)
what do the simplest types of condensation polymers contain
-2 monomer types with same functional groups
what is a diol
a molecule which contains two alcohol functional groups such as ethane diol
how is polyester formed by condensation polymerisation
diol+dicarboxylic acid—->condensation polymer +water
what is a dicarboxylic acids
a molecule that contains 2 carboxylic functional groups
what is an example of a condensation polymer
polyester
what is the diff in monomers between addition and condensation polymerisation
addition-only 1 monomer with c=c bond
condensation=2 monomer types with same func groups or 1 with diff
what is the diff in products formed between addition and condensation polymerisation
addition-1 formed
condensation-2 formed
what is an example of a naturally occuring polymer
-amino acids
polypeptides
DNA molecules
how are amino acids formed
using 2 func groups
amino group and acidic carboxyl group
what is an amino group and a carboxyl group
NH2
-COOH
how are polypeptides formed
amino acids by condensation polymerisation
what is the smallest/simplest amino acid
glycine
what are examples of proteins in the body
enzymes
haemoglobin
antibodies
what is the diff between a polypeptide and protein
polypeptide is a protein monomer
what gives proteins diff properties and shapes
order of amino acids
what does dna have and do
genetic instructions
allows organism to develop and operate
what makes up dna
2 polymer chains of monomers called nucleotides
what makes up nucleotides
molecules called bases
a c t and g
phosphate
sugar
what gives a polymer its double helix structure
bases on diff polymer chain form cross links holding nucleotide together
what do the bases act as
code for the organisms genes
what are sugars
small molecules that contain carbon oxygen and hydrogen
what is the term for the simplest unit of sugar
monosacharide
how are starch and cellulose made by smaller sugars
by condensation polymerisation to form polysacharides
properties of polyethene/thene
strong and easy to shape
useful as a plastic
uses of polythene
carrier bags
drink bottles
dustbins
cling film
washing up bowls
property of polypropene
strong and tough as a plastic
uses of polypropene
carpets
milk crates
ropes`
uses of the first 4 alcohols
as fuels
● uses of methanol:
: chemical feedstock, in anti-freeze, to make biodiesel
● uses of ethanol:
● Ethanol: the main alcohol in alcoholic drinks, used as a solvent and fuel
structure of low density polythene
branched polymer chains
randomly arranged molecules
structure of high density polythene
less branching of polymer chains
closely lined molecules
uses of low density polythene
and properties
-Most carrier bags, bubble wrap
-Flexible, unreactive, can be made into films
properties of high density polythene
and uses
Strong, flexible, resists shattering, resists chemical attack
Plastic bottles, pipes, buckets
properties of thermosoftening polymers
melt when heated
recyclable
why do thermosoftening polymers melt when heated
no covalent bonds betw neighbouring polymer molecules so can move over each other when heated and the plastic melts.
properties of thermosetting polymers
char and burn but dont melt when heated
strong covalent bonds
uses of thermosetting polymers
electrical plugs
properties of carboxylic acids
unpleasant smells and tastes
higher bp than water
not flammable
how is ethanol from alcoholic drinks made
fermentation in presence of yeast
forms ethanol +co2
equation for fermentation
glucose—–>ethanol+carbon dioxide
yeast catalyst
why must fermentation be warm
as yeast is a living microorganism and so its enzymes dont denature
pros and cons of fermentation
cons
-slow/emits co2 as waste
pros
renewable source of energy
only needs heating to 37 degrees
pros and cons of ethene+water
cons-
non renewable/needs lots of energy
pros-
faster than fermentation
100% atom economy
alcohols react with pottasium dichromate(oxidising agent)to produce
a carboxylic acid
alcohols react with air(combustion/complete/incomplete) to produce
co2 +water
combustion
incomplete=soot/carbon monoxide
ethanol +sodium
colourless sodium ethoxide solution+h2 gas(fizzes)
alcohol+water
ph7
neutral solution
colour change in alcohol oxidation
can happen in air so none
-oxidising agent acidified pottasium dichromate
orange to green
alcohol formula
cNh2N+1OH
carboxylic acid formula
cNh2N+1COOH
n=carbon atoms -1
ph strength order
ethanol
nitric
hcl
sulfuric
methanoic
hcl
sulfuric
nitric
methanoic
ethanol
use of ethanoic acid
making vinegar
making esters
test for carboxylic acid
react with sodium bicarbonate-see brisk effervescence
react with sodium carbonate to produce co2
eg of naturally occuring polymers
proteins
carbs
dna
eg of polypeptide
protein
peptide bond
ocnh
how many nucleotides are present in Dna
4
how do nucleotides form polymers and what do we call the polymer
lots of monomers join to form polynucleotide by condensation polymerisation
how many bases code for amino acid
3
what makes the backbone of a polynucleotide
sugar and phosphate
why do a and t attract
and c and g
2 attractions between a-t
3 between c-g
these are imf(h-h bonds)
