chemistry topic 7 organic chemistry Flashcards
what is a hydrocarbon?
any compound that is formed from carbon and hydrogen atoms only
what is the general alkane formula?
CnH2n+2
what are the first four alkanes ?
methane ethane propane butane
what does it mean when the hydrocarbons are shorter regarding their viscosity?
their less viscous
the shorter a hydrocarbon chain the more volatile it is what does this mean?
it turns into a gas at a lower temperature (lower its boiling point)
the shorter a hydrocarbon is the easier it is to set fire to it? what is the word for this?
flammable
what is the equation for the complete combustion of any hydrocarbon with oxygen?
hydrocarbon + oxygen = carbon dioxide + water
what happens to the carbon and hydrogen from the hydrocarbon in combustion?
they are oxidised ( gain oxygen)
what are hydrocarbons used as?
fuels
why are hydrocarbons used as fuels?
due to the amount of energy released when they combust completely
what is used to separate crude oil?
fractional distillation
what is crude oil?
a fossil fuel formed by the remains of plants and animals , mainly plankton
where is crude oil found and drilled up from?
rocks
what is fractional distillation used to do?
separate hydrocarbon fractions
what is crude oil a mixture of?
loads of different hydrocarbons
what happens first in fractional distillation?
the oil is heated until most of it has turned into gas
in fractional distillation where do the new gases go?
into the fractionating column
in fractional distillation, what do the longer hydrocarbons have?
high boiling points
in fractional distillation, where do the long hydrocarbons condense back into liquids in drain out of the column?
they drain out of the column early on , when they’re near the bottom
in fractional distillation, what do the shorter hydrocarbons have ?
lower boiling points
in fractional distillation, where do the shorter hydrocarbons condense and drain out?
much later on, near the top of the column where its cooler as they don’t have boiling points as high
what is the end result of fractional distillation?
each fraction contains a mixture of hydrocarbons that all contain a similar amount of carbon atoms
what does oil provide the fuel for?
most modern transport
what industry uses hydrocarbons to make new compounds for use in things like polymers, solvents etc?
the petrochemical industry
what are two examples of families in the homologous series?
alkanes and alkenes
why are short hydrocarbon chains good for making fuels in high demand?
they are highly flammable
why are long chain hydrocarbon not useful for making fuels in high demand?
they form thick gloopy liquids like tar
as a result of long chain hydrocarbons being not useful what normally happens?
they are turned into smaller , more useful ones by a process called cracking
what is cracking?
a thermal decomposition reaction
what is cracking via thermal decomposition?
breaking down molecules by heating them
what happens first in cracking via thermal decomposition?
heat and turn the long chain hydrocarbons into gas
in thermal decomposition, what happens to the vapour(gas)?
the vapour can be passed over a catalyst
what happens when the gas passes over the catalyst?
the long chain molecules split apart on the surface on the specks of catalyst
what type of cracking is this when using a catalyst?
catalyst cracking
what is steam cracking?
when you vaporise the hydrocarbons, mix them with steam and heat to a very high temperature
why are alkenes unsaturated?
they have a double carbon-carbon bond
what are the first four alkenes?
ethane, propene, butane and pentene
what is the general formula for alkenes?
CnH2n
in alkenes how many double bonds does there have to be?
1
when you burn alkenes in air instead of oxygen what happens?
incomplete combustion
what is incomplete combustion?
as well as carbon dioxide and water produced from combustion you can also get carbon and carbon monoxide
what does incomplete combustion result in?
a smoky yellow flame and less energy being released compared to complete combustion of the same compound
the equation for incomplete combustion always has to be what?
balanced
what happens when orange bromine water is added to a saturated compound?
no reaction will happen and it will stay bright orange
what are plastics made up of?
long-chain molecules called polymers
what are polymers normally based on?
carbon based
what are most monomers made up of?
alkenes
what do the monomers that make up addition polymers have?
a double covalent bond
what is addition polymerisation?
lots of unsaturated alkenes can open up their double bonds and join together to form polymer chains
what is the formula of ethene?
C2H4
what is the formula of propene?
C3H6
what is the formula of butene?
C4H8
what is the formula of pentene?
C5H10
in a large amount of oxygen what do alkenes do?
combust completely
when alkenes are burned in air what tends to happen?
incomplete combustion
what is produced from complete combustion of alkenes?
only water and carbon dioxide
what is produced from incomplete combustion of alkenes?
carbon dioxide water carbon monoxide and carbon
what is the standard equation for the incomplete combustion of alkenes?
alkene + oxygen = carbon+ carbon monoxide+ carbon dioxide+ water
what does incomplete combustion result in ?
a smoky yellow flame, and less energy being released in comparison to complete combustion of the same compound
what do the products of incomplete combustion depend on?
how much oxygen is present
what is a functional group?
a group of atoms in a molecule that determines how that molecule typically reacts
what functional group do all alkenes have?
double carbon CC bond
most of the time how do alkenes react?
via addition reactions
what happens in an addition reaction?
the carbon carbon double bond will open up to leave a single bond and a new atom is added to each carbon
what is addition of hydrogen knows as?
hydrogenation
how does hydrogen react with alkenes?
the hydrogen opens up the double bond to form the equivalent, saturated, alkane
in hydrogenation when does the alkene react?
in the presence of a catalyst
how do halogens react with alkenes?
the molecules formed re saturated, with the CC carbons each becoming bonded to a halogen atom
how do bromine and ethene react together?
to form dibromoethane
what can be used to test for alkenes?
the addition of bromine to a double bond
how do you use bromine to test for alkenes?
the bromine will add across the double bond, making a colourless dibromo-compound
what happens when bromine is added to a saturated compound?
no reaction will happen and it will stay bright orange
when alkenes react with steam what happens?
water is added across the double bond and an alcohol is formed
how is ethanol made?
mixing ethene with steam and passing it over a catalyst
how is ethanol made industrially?
after the reaction, the reaction mixture is passed into a condenser. Ethanol and water have a higher boiling point than ethene so both condense whilst any unreacted ethene is recycled back into the reactor. The alcohol is then purified in fractional distillation
what are polymers?
long molecules formed when lots of small molecules called monomers join together
what do polymers usually make up?
carbon based plastics
what are monomers usually in alkenes?
alkenes
what are the monomers that make up additional polymers made of?
double covalent bond
what is addition polymerisation?
when unsaturated molecules open up their double bonds and join together to form polymer chains
when monomers react in addition polymerisation what is the only product?
the polymer, so an addition polymer contains exactly the same type and number of atoms as the monomers that formed it
how do you draw the displayed formula of an addition polymer from the displayed formula of its monomer?
draw the two alkene carbons, replace the double bond with a single bond and add an extra single bond to each carbon. fill in surrounding group the same and add brackets with repeating units n at bottom right
how do you get the displayed formula of the polymer to the displayed formula of the monomer?
draw out the repeating bit of the polymer, get rid of the two bonds going out through the brackets and add a double bond to the carbons
what is the general formula of an alcohol?
CnH2n+1OH
what is an alcohol with 2 carbons?
C2H5OH
all alcohols contain what group?
OH group
how do you draw alcohols?
draw your C with H bonds and an OH bond
what are the four first alcohols?
methanol, ethanol, propanol and butanol
what property do alcohols have?
they are very flammable
what kind of combustion do alcohols undergo In air?
complete combustion to produce carbon dioxide and water
what relationship does methanol, ethanol, propanol and butanol have with water?
they are soluble
what ph does methanol, ethanol, butanol and propanol have in their solutions?
neutral
what do the first four alcohols react with and what product does the reaction produce?
sodium and the product is hydrogen
what do alcohols produce when they are oxidised?
a carboxylic acid
different alcohols form different carboxylic acids. what do methanol and ethanol form?
methanoic acid and ethanoic acid
why are alcohols such as methanol and ethanol used as solvents in industry?
they can dissolve most things water can dissolve but also what water cant dissolve (hydrocarbons oils and fats)
the first four alcohols are used as fuels. what are some examples of this?
ethanol is used in spirit burners as it burns cleanly and non smelly
how is ethanol usually made?
via fermentation
what does fermentation use?
an enzyme in yeast to convert sugars to ethanol. carbon dioxide is produced
what is the equation for fermentation?
sugar with arrow plus yeast= ethanol + co2
in what conditions does fermentation happen fastest?
temps of around 37 degrees in a slightly acidic solution under anaerobic conditions (no oxygen)
why does it work best under these conditions?
under these conditions the enzyme in yeast works best and if the conditions were different the enzyme could work slower or denature
what functional group are carboxylic acids?
COOH
what names do carboxylic acids end in?
anoic acid
what is the formula for methanoic acid?
HCOOH
what is the formula for ethanoic acid?
CH3COOH
what is the formula for propanoic acid?
C2H5COOH
what is the formula for butanoic acid?
C3H7COOH
how do carboxylic acids react?
like other acids, with carbonates to produce salt, water and co2
what names do the salts form with carboxylic acids?
ending in anoate
what happens when carboxylic acids dissolve in water?
they ionise and release H+ ions resulting in an acidic solution
what does it mean when carboxylic acids don’t ionise completely?
they just form weak acidic solutions meaning they have a higher PH than aqeous solutions of strong acids with the same concentration
what can be made from carboxylic acids?
esters
what functional group do esters have?
COO
what are esters formed from?
an alcohol and carboxylic acid
what sort of catalyst is usually added to make an ester?
acid catalyst
what is the equation for making an ester?
alcohol + carboxylic acid = plus catalyst ester +water
what can be made from ethanoic acid and ethanol with a catalyst?
Ethyl ethanoate
what does condensation polymerisation involve?
monomers which contain different functional groups
what happens to the monomers in condensation polymerisation?
the monomers react together and bonds form between them, making polymer chains
for each new bond formed in condensation polymerisation what happens?
a small molecule (for example, water) Is lost. this is why its called condensation polymerisation
what is the simplest type of condensation polymers?
contains two different types of monomer, each with two of the same functional groups
how can a polyester be made by condensation polymer?
a diol (ethane diol)+ a dicarboxylic acid (hexanedioic acid) gives a polyester + water
how many numbers of types of monomers are there in addition polymerisation?
only one type of monomer containing a double carbon bond
how many number of products is there from addition polymerisation?
only one product fromed
how many functional groups are involved in polymerisation?
carbon carbon double bond in monomer
how many number of types of monomers are there 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 number of products are made from condensation polymerisation?
two types of product- the polymer and a small molecule (e.g. water)
how many functional groups are involved In condensation polymerisation?
two reactive groups on each monomer
where are polymers found apart from the lab?
the natural world
what two functional groups does an amino acid contain?
a basic amino acid group(NH2) and an acidic carboxyl group(COOH)
what is an example of an amino acid?
glycine- the smallest and simplest amino acid possible
what polymers can amino acids form?
polypeptides via condensation polymerisation
how can amino acids form a polymer chain?
the amino group of an amino acid can react with the acid group of another, and so on, to form a polymer chain
for every new bond formed in amino acids what is lost?
water
what are proteins known as?
one or more long chains of polypeptides
what important uses to proteins have in the body?
enzymes work as catalysts, haemoglobin transports oxygen, antibodies from part of the immune system and the majority of body tissue is made from proteins
polypeptides and proteins can contain what?
different amino acids in their polymer chains
where is DNA found?
in every living thing and many viruses
what does DNA contain?
genetic instructions that allow the organism to develop and operate
what is the structure of DNA like?
a large molecule that takes a double helix structure
what is DNA made of?
two polymer chains of monomers called nucleotides
what does each nucleotide contain?
a small molecule known as a base. there are four different bases known as ACGT
what do the bases on each polymer chain do with each other?
pair up and form cross links keeping the two strands of nucleotides together and giving the double helix structure
what does the order of bases act as?
a code for an organisms genes
what are sugars?
small molecules that contain carbon, oxygen and hydrogen
what do sugars react together through polymerisation to form?
large polymers eg starch and cellulose
what gives proteins different properties and shapes?
the order of amino acids
