Organic Chemistry Flashcards
what is crude oil?
a finite resource found in rocks and is the remains of an ancient biomass consisting mainly of plankton that was buried in mud; a mixture of a very large number of compounds
what is crude oil mainly made of?
hydrocarbons
what is a hydrocarbon?
a molecule made up of carbon and hydrogen atoms only
what is the general formula for the homologous series of alkanes?
CₙH₂ₙ₊₂
what is the general formula for the homologous series of alkenes?
CₙH₂ₙ
list the first four members of alkanes
methane, ethane, propane, butane
what are the features of the alkane homologous series?
- formula differ by CH₂
- same general formula
- similar chemical formula
- BP increases as chain length increases
what are the features of the alkene homologous series?
- unsaturated
- the double carbon bond is the functional group
what is the functional group?
reactive part of a formula
why can’t methene (1 carbon alkene) exist?
it can’t form the double carbon bond required to be an alkene
list the first four members of alkenes
ethene (C₂H₄), propene (C₃H₆), butene (C₄H₈), pentene (C₅H₁₀)
how many bonds does each carbon atom in an alkene form?
4
what are the 2 types of reaction that alkenes undergo?
combustion and addition
what happens when alkenes undergo combustion?
it is usually incomplete and a smoky flame can be observed
what happens in addition reactions with alkenes?
the double bond breaks to form a single bond and atoms are added to bond with the carbons
what are the conditions required for the addition of alkenes with halogens?
no conditions required; RTP
what is the word equation for the addition of alkenes with halogens?
halogen + alkene => halogenalkane
what happens in the addition of alkenes with halogens?
1 halogen atom will go on each carbon atom that was previously in the double bond
what are the conditions required for the addition of alkenes with hydrogen?
nickel catalyst
what is the word equation for the addition of alkenes with hydrogen?
alkene + hydrogen ⇒ alkane
what are the conditions for the addition of alkenes with water?
acid catalyst, high temp, high pressure
what is the word equation for the addition of alkenes with water?
alkene + water ⇒ alcohol
what happens in the addition of alkenes with water?
one hydrogen atom goes on one carbon from the double bond, the OH (functional group) will go on the other
are alkanes or alkenes unreactive?
alkanes are unreactive whereas alkenes are reactive
what is the test for alkenes?
bromine water (reacts with alkenes not alkanes) changes orange to colourless
are alkanes saturated or unsaturated?
saturated
are alkenes saturated or unsaturated?
unsaturated
what does saturated mean??
A molecule containing only single bonds between carbon atoms
what is cracking?
the breaking down of larger alkane hydrocarbon molecules into smaller, more useful ones
what are the 2 types of cracking?
steam and catalytic
what does steam cracking require??
requires high temp and steam
what does catalytic cracking require??
requires high temp and catalysts
what do the products of cracking include?
alkenes and alkanes
what are the uses of products of cracking?
- high demand for alkanes with small molecules so some of the products are useful as fuels
- alkenes used to produce polymers and as starting materials for production of other chemicals
how do you write equations for the products of cracking?
- sum of carbons and hydrogens must be equal on each side
- both alkenes and alkanes produced
what happens as chain length of hydrocarbons increases?
- BP increase
- viscosity increases
- flammability decreases (as, to burn, it needs to be a gas or evaporate easily)
what is the equation for the complete combustion of a hydrocarbon?
fuel + oxygen ⇒ carbon dioxide + water
what is the equation for the incomplete combustion of a hydrocarbon?
fuel + oxygen ⇒ carbon monoxide + water
what is a fraction?
mixture of molecules with a similar BP and similar number of carbon atoms
what are the fractions produced from fractional distillation of crude oil hydrocarbons?
Real Gasoline Keeps Dirty Fuel Bitchin’
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
what are refinery gases?
bottled gas
what is gasoline used for?
fuel for cars
what is kerosene used for?
fuel for aeroplanes
what is diesel used for?
fuel for vans and trucks
what is fuel oil used for?
fuel for ships and power stations
how does the viscosity of fractions produced from fractional distillation of crude oil hydrocarbons change going down the column?
it increases
what is bitumen used for?
used to lay roads
describe the process of fractional distillation of crude oil hydrocarbons
- crude oil heated and evaporates to vapour
- vapour is fed in near bottom of column
- column is kept very hot at bottom and cooler near top
- crude oil enters as mixture of gases with different BP
- gases move up column and condense at different heaights
- hydrocarbons with highest BP (larger molecules) condense near bottom
- hydrocarbons with lowest BP (smaller molecules) condense near top
what are the properties and features of alcohols?
- contain the functional group -OH
- can be represented as C₂H₅OH to show the functional group
- miscible with water to form neutral solutions
- can be used as solvent as can dissolve organic substances - so are often used in perfumes
- small chain alcohols can be used as foods
- ethanol is main alcohol in alcoholic drinks
list the first 4 alcohols
- methanol (CH₄O or CH₃OH)
- ethanol (C₂H₆O or C₂H₅OH)
- propanol (C₃H₈O or C₃H₇OH)
- butanol (C₄H₁₀O or C₄H₉OH)
describe the combustion of alcohols
- undergo complete combustion to produce carbon dioxide and water
- burn with a blue flame
alcohol + Na -> ?
salt + H2
what happens in the reaction between sodium and an alcohol?
can see fizzing but this is less then when Na reacts with water, as Na sinks in ethanol but floats on water (less dense)
alcohol + O2 -> ?
carboxylic acid
what are the 2 ways that alcohols can be oxidised?
- react with oxygen in the air
- by reacting with an oxidising agent
what is potassium dichromate?
an oxidising agent; orange but turns green in alcohol and is used in roadside breathalysers
alcohol + carboxylic acid -> ?
ester
what is an example of an ester?
ethyl ethanoate
what are the requirements for the reaction of alcohol with a carboxylic acid?
a sulfuric acid catalyst and heat
what are the conditions required for making ethanol using fermentation?
- sugars are aqueous
- yeast (catalyst) is added
- mixture is kept at 30-37 degrees C which is the optimum temp for yeast and prevents it denaturing
- anaerobic - if oxygen is present, the ethanol could oxidise to form ethanoic acid
what kind of process is making alcohol through fermentation?
reaction takes a few days so is a batch process
what is the symbol equation for making ethanol through fermentation?
C₆H₁₂O₆ ⇒ 2C₂H₅OH (aq) + CO₂
how do you purify ethanol in fermentation?
must be separated from yeast and water solution using filtration then fractional distillation (a bunsen burner can’t be used to separate water and ethanol as ethanol is flammable - use an electric heater)
how is ethanol made using hydration?
ethene (from crude oil) is reacted with steam to form pure ethanol
compare using hydration and fermentation to make ethanol
- hydration has 100% atom economy
- hydration is quicker than fermentation but needs harsher conditions
- hydration is less labour intensive than fermentation
what are the features of carboxylic acids?
- functional group -COOH
- weak acids
list the first 4 carboxylic acids
- methanoic acid (HCOOH)
- ethanoic acid (CH₃COOH)
- propanoic acid (C₂H₅COOH)
- butanoic acid (C₃H₇COOH)
carboxylic acid + metal carbonate ⇒
salt + water + carbon dioxide (neutralisation)
carboxylic acid + alcohol ⇒
ester + water (required sulfuric acid catalyst)
why is the reaction between a carboxylic acid and a metal carbonate slow?
they are weak acids
what are esters used for?
have fruity smells so are used in: solvents in perfumes and fruity flavourings
what is condensation polymerisation?
formation of long chain molecules from lots of small molecules joining together with another small molecule produced as well
dicarboxylic acid + dialcohol (same functional group of OH) =>
a polyester + water
what is the ester link?
O-C=O
what is addition polymerisation?
many monomers joining together to form very large molecules (polymers) where the double bonds open up
why, in addition polymers, does the repeating unit have the same atoms as the monomer?
no other molecule is formed in the reaction
what are amino acids?
molecules which have at least two functional groups.
what are starch and cellulose?
carbohydrate polymers made from the monomer glucose
what are proteins?
polymers made from the monomer amino acids
what functional groups do all amino acids have?
-NH2 group and the carboxylic acid group -COOH
what is the H-N-H functional group?
functional group in amino acids which reacts with acids
what is the O=C-O-H functional group?
carboxylic acids functional group found in amino acids which reacts with bases
what do amino acids react by condensation polymerisation to produce?
polypeptides
Amino acids react by condensation polymerisation which means what??
for every monomer which is added to the growing polymer chain, one molecule of water is also produced.
In addition polymerisation, the monomers must have a what bond?
C=C double bond
in condensation polymerisation, the monomers need what?
do not need a C=C double bond but they do need two functional groups.
what is the peptide link?
the amide linkage that forms between the carboxylic acid group of one amino acid and the amine group of another amino acid: O=C-N-H
what is DNA?
- 2 polymer chains
- 4 different monomers/nucleotides
- double helix
- formed by condensation polymerisation
