organic chemistry Flashcards
uses of crude oil
plastic
petrol
cosmetics
what is crude oil (generally & scientifically) and how is it formed
a fossil fuel (finite resource) found in rocks. a mixture of hydrocarbons
formed over millions of years when plant and animal remains, mainly plankton, get buried in mud and turn to crude oil due to pressure and temp
what id a hydrocarbon
compound of carbon and hydrogen atoms only
what is an alkane and how can you tell by the formula/word
- simplest hydrocarbon: all C—C single covalent bonds
- a homologous series
- saturated compounds
C(n)H(2n+2)
(prefix)-ane
homologous series meaning
group of organic compounds that react in a similar way to
saturated compounds meaninh
all carbon atoms are fully bonded to hydrogen atoms
alkanes in increasing order of carbon atoms
methane CH4
ethane C2H6
propane C3H8
butane C4H10
how do hydrocarbon properties change as they get larger
as size increases:
- viscosity increases
- boiling point increases
- flammability decreases
what happens when a hydrocarbon combusts (is burned) with plenty of oxygen
complete combustion, energy released
carbon and hydrogen react with oxygen, becoming oxidised.
hydrocarbon + oxygen —> co2 + water (+energy)
how to balance equation for combustion
in this order
C
H
O
how can you get one specific compound from crude oil
fractional distillation
how does fractional distillation work
• crude oil is heated until evaporated
• vapour enters fractionating column
• column has temperature gradient (hot at bottom)
• meaning longer hydrocarbons will condense back to liquid nearer to the bottom, because they have got a higher boiling point
• smaller hydrocarbons continue rising up the column and condense nearer to the top as they have lower boiling point
• very short chain hydrocarbons with very low boiling points do not condense, they get removed from top as LPG
• crude oil is now separated into liquid fractions with similar number of carbon atoms. fractions removed
order of fractions of compounds (longest to shortest)
heavy fuel oil
diesel oil
kerosene
petrol
LPG (liquified petroleum gas)
what can fractions be used as feedstock (chemicals that make other chemicals)
solvents
lubricants
detergents
polymers
what is cracking
breaking down a long chain alkane to produce smaller, more useful molecules - shorter chain alkanes, and alkenes
why do we need cracking
long chain hydrocarbons are not very flammable, so do not make good fuels. short chain hydrocarbons needed
how do you do cracking with high temperatures and a catalyst, and what is the name
catalytic cracking
- heat LCH to vaporise them
- pass over a catalyst, where they split apart
how do you do cracking with high temperatures and steam and what is it called
steam cracking
- heat LCH to vaporise them
- mix with steam
- heat at high temp
what is an alkene, some properties compared with alkanes, and how can you tell by the formula/word
hydrocarbons with functional group C=C
- two fewer H atoms than alkanes as carbon atoms always have 4 bonds - unsaturated
-more reactive than alkanes
C(n)H(2n)
(prefix)-ene
uses of alkenes
- to make polymers
- starting material for other useful chemicals
how can you test for alkenes
shake with bromine water (which is orange) in a test tube.
bromine turns colourless if alkene is present
functional group meaning
feature of molecule that determines how it reacts
what happens when an alkene combusts in air with word equation
incomplete combustion - burn with a smoky yellow flame and less energy produced
alkene + oxygen —> carbon + carbon monoxide + water (+ energy)
what happens when alkenes react with hydrogen and what is it called
hydrogenation
in presence of a catalyst, H2 opens up the double bonds to form the equivalent, saturated alkane (double carbons bond to 2 Hs)
what happens when alkenes react with water/steam and what is it called
hydration
in 300° and in presence of a catalysts, H2O opens double bond to produce alcohol (double carbons bond to H and OH)
what happens when alkenes react with halogens
halogen opens double bond (double carbons bond with 2 halogens) to form
di-(halogen prefix)-o-(alkane)
e.g:
dibromoethane
dichloropropane
uses of alcohols
solvent
fuel
alcoholic drinks
what is an alcohol and how can you tell by formula/word
hydrocarbons with functional group OH
C(n)H(2n+1)OH
(prefix)-anol
how can formula of alcohols look different to other hydrocarbon formulas
like terms do not have to be together eg
CH3CH2CH2OH
how can ethanol be made
hydration of ethene
fermentation
how does fermentation work and what are the advantages and disadvantages
in 30°, anaerobic (no oxygen) conditions:
sugar solution e.g glucose
—(yeast)—> ethanol + co2
- low temp, little energy required
- sugar comes from plants: renewable
- however product is ethanol (aq), meaning it still needs to be distilled to get pure ethanol, which requires energy
describe solubility of alcohols
soluble in water and form neutral solutions
as number of carbon atoms increases, solubility decreases
describe the reaction of alcohol with sodium
sodium (prefix)-oxide and hydrogen gas is produced
how do alcohols react with an oxidising agent
carboxylic acid and water produced
what happens when alcohols combust
complete combustion
what is a carboxylic acid and how can you tell by the formula/word/diagram
hydrocarbons with functional group COOH
- like terms do not have to be together eg C2H5COOH
- (prefix)-anoic acid
- regular diagram just like alkanes, however one C atom is bonded to two O atoms: one double, one single and bonded to another H atoms
how do carboxylic acids react in water
as they dissolve, they ionise to produce (prefix)-anoate ion and H+
- reversible reaction
- as they only partially ionise, they are weak acids
how do carboxylic acids react with metal carbonates
it will form (metal) (prefix)-anoate, water, and co2
how do carboxylic acids react with alcohols, with example of ethanoic acid and ethanol
in presence of a catalyst, ester and water produced
ethyl ethanoate and water produced
what is a polymer and what are the different kinds
formed when lots of monomers (small, identical molecules) joined together
addition and condensation
what is an addition polymer, and how can you tell from the diagram/word
where the monomers are unsaturated, so alkenes, as the double bonds open up to join together
poly((alkene))
drawn as a repeating unit, where n presents number of monomers:
properties of addition polymers
- repeating unit has same atoms as monomer (all atoms in monomer are in polymer, none added)
what is a condensation polymer
where monomers each contain two of the same functional groups
(different groups but the
what is a polyester and how is it made
a condensation polymer
when a diol (monomer with two alcohol groups
HO—[]—OH
and a dicarboxylic acid (monomer with two carboxylic acids groups)
HOOC—[]—COOH
alcohol + carboxylic acid —> ester + water
so when the monomers react, maximum amount of H20 molecules in equation are created. rest forms the polyester
what do boxes represent in condensation polymerisation equations
hydrocarbon chain
what are amino acids
molecules with two functional groups
- amine group NH2
- carboxylic group COOH
example: glycine
what happens when two amino acids react and why
condensation polymerisation as they have two different functional groups
form polypeptides if monomer is the same, and protein when monomers are different
lose water molecule for every bond formed
repeating unit for polypeptides (glycine only)
-(-HNCH2COO-)-n + nH2O
how is dna a naturally occurring monomer
nucleotide monomers (A, T, G, and C) form two polymer chains that twist in a double helix
naturally occurring polymers
dna - polymers of nucleotides
protein - polymers of amino acids
starch - polymers of glucose
cellulose - polymers of glucose
