Organic Chemistry Flashcards
What is a hydrocarbon made out of?
- carbon
- hydrogen
what is the simplest type of hydrocarbon?
general formula?
- alkanes
- CnH2n+2
- homologous series
- saturated compound
what are the first four alkanes?
- methane
- ethane
- propane
- butane
explain how properties of hydrocarbons are affected?
- shorter carbon chain
- less viscous
- more volatile (lower bpt)
- more flammable
how do properties of hydrocarbons affect how they are used for fuels?
- short chain hc w/ lower bpt are used as bottled gases
- stored under pressure as liguids in bottles
what is complete combustion of hydrocarbons?
why is it used?
- both carbon and hydrogen oxidised
- waste products are CO2 and water
- hc used as fuels as release lots of energy when combust completely
why are fossil fuels non-renewable?
- used up fatser than being produced
- finite so will run out
how is crude oil seperated using industrial fractional distillation?
- oil heated until most gas and enter fractionating column
- column has temp gradient
- long hc have high bp, condense first at bottom where its hot
- short hc have low bp, condense drain out later near the top where its cooler
- mixture sperayed into different fractions: similar carbon atoms/bp
what fractions of hc are used for different fuels?
3: LPG
8: petrol
15: kerosene
20: diesel oil
40: heavy fuel oil
what do petrochemical industry use hc for?
- feedstock to make new compounds for
- polymers
- solvents
- lubricants
- detergent
what is organic compounds?
why is there a large variety of them?
- contain carbon atoms
- bond together to form different homologous series
why do short chain hc make good fuels?
why not long chain?
- flammable
- high in demand
- long chain form thick gloopy tar
why is cracking used on long chain hc from fractional distillation of crude oil?
-make smaller, more useful hc
what are the products of cracking?
- alkane
- alkene used as starting material for polymers
what reaction is cracking?
- thermal decomposition reaction
- break molecules down by heating
what is catalytic cracking?
- heat long chain hc to vaporise
- vapour passed over hot-powered aluminium oxide catalyst
- long chain hc split apart on surface of specks of catalyst
what is steam cracking?
- heat long chian hc to vaporise
- mix vapour with steam
- heat to very high temp
what are alkenes?
general formula?
reactivity?
- hc with C=C
- unsaturated
- CnH2n
- C=C open to single bond so carbon can bond with other atom making it more reactive than alkanes
what are the first four alkenes?
- ethene
- propene
- butene
- pentene
why do alkenes not combust completely?
what are the products?
- not enough oxygen in air
- incomplete combustion
- smoky yellow flame
- less energy
- produce CO or C
what is a functional group?
- group ofatoms in molecule
- determines how typically reacts
how do alkenes react generally?
- addition reactions
- C=C opens up and new atom added to single bonds
what is hydrogenation?
- hydrogen reacts with alkene in presence of catalyst
- forms alkane
what is hydration?
- alkenes react with steam in presence of catalyst
- water added across double bond
- form alcohol
how do you make ethanol industrially?
-mix ethene with steam and pass over catalyst to make ethanol
reaction mixture passed from reactor into condenser
- ethanol and water have higher bp than ethene so both condense
- unreacted ethene gas recycled back into reactor
alcohol then purified from mixture by fractional distillation
what is halogenation?
give example
- addition reaction with bromine/chlorine/iodine
- saturated
- bromine and ethene = dibromoethane
how can you use the addition of bromine to double bond to test for alkenes?
- when orange bromine water added to saturated compound: stays orange
- when added to alkene: bromine adds across C=C and solution decolourised
what are polymers?
- long molecules formed when small molecule monomers join
- polymerisation
plastics are made of polymers
- carbon based
- monomers often alkenes
what are addition polymers made up of?
-monomers with double covalent bond
what is addition polymerisation?
-unsaturated monomers (alkenes) open double bond and join to form long polymer chains
what are the products in addition polymerisation?
- addition polymer
- contains same type/number atoms as monomer that formed it
what are alcohols?
general formula?
- hydration of alkene
- CnH2n+1OH
what are the first four alcohols?
- methanol
- ethanol
- propanol
- butanol
what are the properties of alcohol?
- flammable so combust completely
- soluble in water, neutral pH solution
- react with sodium produce hydrogen
- oxidise to form carboxylic acid
why are alcohols like methanol and ethanol used as solvents in industries?
- can dissolve things water can and can’t
- hc/oil/fats
how can ethanol be used as a fuel?
- spirit burners
- burns cleanly
- odourless
what is fermentation?
what can it make?
- uses enzyme in yeast to convert sugars into ethaniol
- CO2 produced
- reaction occurs in solution so product is aqueous
what conditions are needed for fermentation?
- 37°C
- slightly acidic solution
- under anaerobic conditions (oxygen)
what would happen if fermentation happened with the wrong conditions?
- lower pH/higher temp or higher pH/lower temp
- enzyme denatured
- work at slower rate
what are carboxylic acids?
functional group?
- formed when alcohol oxidises
- COOH
what are the first four carboxylic acids?
- methanoic acid
- ethanoic acid
- propanoic acid
- butanoic acid
carboxylic acid + carbonate
salt + water + CO2
what happens when carboxylic acids dissolve in water?
- partially ionise
- few molecules release H+ ions
- weak acidic solution
- higher pH (less acidic) than strong acids with same concentration
what are esters?
functional group?
what acid catalyst can be used?
- alcohol + carboxylic acid –(acid catalyst)–> ester + water
- COO-
- concentrated sulfuric acid
give an example of how ethyl ethanoate can be formed
ethanoic acid + ethanol –> ethyl ethanoate + water
what is condensation polymerisation?
- monomers with different functional groups
- react and bonds form between them makeing polymer chain
- each new bond means small molecule (water) lost
how is the number of types of monomers different for addition and condensation polymerisation?
- ADDITION: only one monomer type containing C=C
- CONDENSATION: two monomer types each containing two of the same functional groups
or
one monomer type with two different functionl groups
how is the number of products different for addition and condensation polymerisation?
- ADDITION: only one product formed
- CONDENSATION: two types of products (polymer and water)
how are the functional groups involved in polymerisation different for addition and condensation polymerisation?
- ADDITION: C=C in monomer
- CONDENSATION: two reactive groups on each monomer
what functional groups do amino acids contain?
give an example
- basic amino group (NH2) and an acidic carboxyl group (COOH)
- glycine
what polymers do amino acids form?
- popypeptides via condensation polymerisation
- amino group reacts with other acid group to form polymer chain
- every new bond water lost
how are proteins made?
what uses do they have in the human body?
- one or more long chains of polypeptides
- enzymes work as catalysts
- haemoglobin transports oxygen
- antibodies part of immune system
- majority of body tissues made from proteins
what gives proteins and polypeptides their properties and shape?
-order of different amino acids in polymer chains
what is DNA?
- contains genetic instructions that allow organisms to develop and operate
- large molecule that has double helix structure
what and how do polymers make DNA?
- two polymer chains of monomers called nucleotides
- each contains small base molecule (A,C,G,T)
- bases on different chain cross links to keep nucleotides together giving double helix structure
- order of bases act as code for organism’s genes
