ORGANIC CHEMISTRY Flashcards
WHAT IS a hydrocarbon
a compound that only contains hydrogen and carbon atoms
what is an alkane
they are saturated hydrocarbons
and they have carbon carbon single bonds
what are the first four alkanes
methane
ethane
propane
butane
what is the general formula for alkanes
CnH2n+2
what happens if you change the length of a carbon chain
the properties of the hydrocarbon change
properties of short hydrocarbons
less viscous
more volatile (lower boiling point)
more flammable
what are the products of the complete combustion of any hydrocarbon
carbon dioxide and water
what can hydrocarbons be used as
they can be used as fuels because of the energy that they release when they combust completely
complete combustion equation
hydrocarbon + oxygen ——- carbon dioxide + water
what is crude oil
it is fossil fuel and contains a mixture of hydrocarbons
how are the different compounds in crude oil seperated
fractional distillation
how does fractional distillation work
the oil is heated until most of it has turned into a gas, the gases then enter a fractionating column
in the column theres a temperature gradient
the longer hydrocarbons have high boiling points, they condense back into liquids and drain out of the column early on, when theyre near the bottom
the shorter hydrocarbons have lower boiling points they condense and drain near the top of the column where its cooler
the crude oil mixture is now separated into different fractions
importance of crude oil
oil provides the fuel for most modern transport
the petrochemical industry uses some of the hydrocarbons from crude oil as feedstock to make new compounds for use in things like polymers solvents lubricants and detergents
what is cracking
splitting up long chain hydrocarbons
why would we crack longer chain hydrocarbons
longer chain hydrocarbons form thick gloopy liquids which aren’t useful and short hydrocarbons are more useful as they are more flammable, so they make good fuels and are in high demand
why is cracking useful
longer hydrocarbon molecules produced from fractional distillation are turned into smaller more useful ones by cracking
what type of reaction is cracking
thermal decomposition reaction
process of catalytic cracking
the first step is too heat long chain hydrocarbons to vaporise them
then the vapour is passed over a hot powdered aluminium oxide catalyst
the long chain molecules split apart on the surface of the specks of catalysts
whats another way of cracking hydrocarbons other than catalytic cracking and how does it work
steam cracking
if you vaporise them mix them with steam and then heat them to a very high temperature
What are alkenes
they are unsaturated hydrocarbons
and they have double carbon carbon bonds
what are the first 4 alkenes and how many c’s does it have
ethene (2cs)
propene (3cs)
butene (4cs)
pentene (5cs)
what is the general formula for alkenes
CnH2n
in a large amount of oxygen, alkenes…..
combust completely to produce only water and carbon dioxide
why is it hard for alkenes to combust completely what happens when this happens
there isn’t enough oxygen in the air for this, so when you burn them they tend to undergo incomplete combustion
what happens in incomplete combustion
carbon dioxide and water are still produced but carbon monoxide and carbon is also produced
what is the equation for incomplete combustion
alkene + oxygen ——- carbon + carbon monoxide + carbon dioxide + water
what is a functional group
is a group of atoms in a molecule that determine how that molecule reacts
why are alkenes a homologous series
because they all have the same functional group and react in similar ways
what is the addition of hydrogen called
hydrogenation
what happens when alkenes react with hydrogen
its in the presence of a catalyst
opens up the double bond to form a single bond
what happens when alkenes react with steam
its passed over a catalyst
water is added across the double bond and an alcohol is formed
how can ethanol be made
mixing ethene with steam and then passing it over a catalyst
what happens when alkenes react with halogens
the c=c carbons become bonded to a halogen atom
becomes a single bond also
how do you test for alkenes
add bromine water to the compound if its an alkene the bromine water will turn colourless
what colour is bromine water
orange
what happens if you add bromine water to an alkane
the bromine water will stay orange as there are no alkenes
what are plastics made up of
they are made up of long chain molecules called polymers
what are polymers
they are long molecules formed by many monomers
what are addition polymers made from
unsaturated monomers
how to draw the displayed formula for an addition polymer
start by drawing the two alkene carbons and then replace the double bond with a single bond and extra bond to each of the carbons
fill in what you need to drawing lines above the carons
draw brackets and then put an n next to it
what functional group do alcohols have and what do they end in
-oh and end in ol
what is the general formula for alcohols
CnH2n+1OH
what are the first 4 alcohols
methanol
ethanol
propanol
butanol
what do all alcohols have in common
they have the functional group oh-
what similar properties do the first four alcohols have
they are flammable and they undergo complete combustion in air to produce carbon dioxide and water
theyre all soluble in water and have a neutral ph
they react with sodium
they can be oxidised by reacting with oxygen to produce a carboxylic acid
what can the first four alcohols be used as
fuels
what can alcohols be used as in industry
solvents
when does complete combustion occur
when theres oxygen
another way that ethanol can be made other than the use of ethene
by fermentation
how does fermentation work
fermentation uses an enzyme in yeast to convert sugars into ethanol carbon dioxide is also produced
what is the word equation for fermentatoin
yeast
sugar ——- ethanol + carbon dioxide
when does fermentation happen fastest
when at 37 degrees in a slightly acidic solution under anaerobic conditions
what functional group do carboxylic acids have
-COOH
what are the first four carboxylic acids
methanoic acid
ethanoic acid
propanoic acid
butanoic acid
how are carboxylic acids drawn
eg CH3COOH
CH3 DRAWN NORMALLY then another single bond to c the
c double bond to o drawn diagonally upwards then
single bond downwards diagonally OH
how do carboxylic acids react with carbonates
they react to produce a salt, water and carbon dioxide
what do the salts formed end in, when in the reaction of an carboxylic acid and a carbonate
eg ethanoic
-anoate
ethanoate
ethanoic acid + sodium carbonate —–
sodium ethanoate + water + carbon dioxide
what happens when carboxylic acids dissolve in water
they ionise and release h+ ions
what functional group do esters have
-COO-
how are esters formed
from an alcohol and a carboxylic acid
what catalyst is usually used when forming an ester
an acid catalyst
what is the word equation for the formation of an ester
acid catalyst
alcohol + carboxylic acid ———————- ester + water
ethanoic acid + ethanol =
(acid catalyst) ethyl ethanoate + water
how to draw esters
take out the OH from the carboxylic acid and take out the H from the start of the alcohol
join the acid and alcohol together with a bond down with the c and the o
separately add the h20 on the side
how many types of monomers in additional polymerisation
only one type containing a c=c bond
no of products in addition polymerisation
only one product formed
functional groups involved in addition polymerisation
carbon carbon double bond in monomer
how many types of monomers in condensation polymerisation
two monomer types each containing two of the same functional groups
or
one monomer type with two different functional groups
how many products formed in condensation polymerisation
two types of product- the polymer and a small molecule
functional groups involved in condensation polymerisation
two reactive groups on each monomer
what functional groups do amino acids contain
a basic amino group NH2 and an acidic carboxyl group (COOH)
what polymers can amino acids form
polypeptides via condensation polymerisation
what are sugars
are small molecules that contain carbon, oxygen, and hydrogen
what small molecule is lost when two amino acids react together to form a new bond
water
amino acids can bond together by condensation polymerisation state the type of polymer formed from this reaction
polypeptides
give three examples of naturally occurring polymers
proteins
starch
DNA
