ORGANIC CHEM-pg 149 + how to draw Flashcards
what is a hydrocarbon
general formula for alkanes
what is a homologous series
compound formed from only H and C atoms
CnH2n+2
a group of organic compounds that react in a similar way and all have the same functional group
what are alkanes, explain why
.
what is a functional group
saturated hydrocarbons/compounds
each carbon atom has 4 single covalent bonds
part of molecule that determines how it will react
first 4 alkanes and their formulas
what is a displayed formula
methane CH₄
ethane C₂H₆
propane C₃H₈
butane C₄H₁₀
a drawing showing all atoms and bonds in molecule
what happens as length of carbon chain (hydrocarbon) gets bigger
the properties of a hydrocarbon affects …….
-viscosity increases (more gloopy, less runny)
-boiling point increases, volatility decreases- higher temp needed to vaporise/condense
-flammability decreases, harder to ignite
how the hydrocarbon is used as a fuel
equation for complete combustion of hydrocarbon fuels
what are the waste products
what is released
-Hydrocarbon + oxygen—> Carbon dioxide + water (and energy)
-Carbon dioxide + water (vapour)
-energy
explain what happens in combustion of Hydrocarbons
why are hydrocarbons used as fuels
the carbon and hydrogen in the fuels are oxidised (gain O₂)
bcse of amount of energy released in complete combustion
what is crude oil x3
-finite recourse in rocks (fossil fuel)
-Formed from remains of an ancient biomass, mainly plankton, that was buried in mud- under high pressure and time, became crude oil
-Mixture of many different compounds, mostly hydrocarbons, mostly alkanes
fossil fuels- coal, oil, gas are all…..
explain why
non renewable- finite recources
Used at faster rate than being formed
-What does fractional distillation do
-Explain how fractional distillation works 4 points
separate hydrocarbons in crude oil into fractions (w/ similar no. of carbon atom)
-Vaporise oil till it turns to gas- gases enter fractionating column
-in column, there is a temp gradient, Hot —> Cool
-longer hydrocarbons = higher boiling points. Condense into liquid + drain out early- near bottom.
Shorter hydrocarbons = lower b.p. Condense + drain out later, near top
-eventually Crude oil mixture separated into fractions w/ similar carbon atom no. so similar bp’s
5 gases u know that are produced from crude oil- rely on in life
From highest to lowest boiling point
.
what is lpg made of
heavy fuel oil-ships
diesel oil-trucks/buses
kerosene-plains
petrol-cars
Liquified Petroleum Gas-camping stoves, heating oil, lubricating oil
-mostly propane and butane
what happens to very short chain hydrocarbons in the fractional column
have really low boiling points
.all throughout the column, the temperature is hot enough to keep these as gas
they cannot condense - taken out from the top still in gas form
the fractions can be processed to produce…….
fuels and feedstock for the petrochemicals industry
what does feedstock mean
the petrochemical industry uses fractions of crude oil as feedstock to make new compounds for use in things like…. x4
a chemical used to make other chemicals
-polymers
-solvents
-lubricants
-detergents
The products of crude oil are all types of…..
The vast array of natural and synthetic carbon compounds is bcse of…
organic compounds (compounds containing carbon)
Carbon atoms ability to form families of similar compounds- different homologous series.
what is cracking
why is it done x2
What are the potential products of cracking x2
2 types of cracking
breaking down hydrocarbons into smaller, more useful molecules
Short chain hydrocarbons= more flammable=good fuels
Fuels w/ small molecules are in high demand
-alkanes, alkenes
-catalytic/ steam
what are alkenes used to produce x2-
some products of cracking are useful as
-Polymers. Starting material for producing other chemicals
-fuels
what type of reaction is cracking
Describe catalytic cracking -3 steps
Describe steam cracking- 3 steps
Thermal decomposition-break down molecules by heating
.
Both MUST be done under high temp (320* +)
.
-vaporise long chain hydrocarbon - heat to gas
-pass vapour over HOT powdered aluminium oxide catalyst
-long chain molecules split apart
-vaporise hydrocarbons
-mix them w/ steam
-heat to VERY high temp
C₅H₁₂ can be cracked into ethene and 1 other hydrocarbon,
Give balanced symbol equation for this
C₅H₁₂ —-> C₂H₄ + C₃H₈
why are alkanes useful as fuels
what are alkenes
they release energy when burnt
hydrocarbonsthat have functional group C=C
general formula for alkenes
why are alkenes unsaturated
why are alkenes more reactive than alkanes
first 4 alkenes
CnH2n
have C=C double bond so have 2 fewer hydrogens than an alkane w/ same carbon number
the C=C double can open up to make a single bond, the two C atoms can bind w/ other atoms
ethene
propene
butene
pentene
Akene+ Oxygen=
when alkenes are burnt in air, alkenes undergo….
standard equation for incomplete combustion of alkenes
what can be seen when alkenes incompletely combust
Carbon Dioxide + Water
incomplete combustion
Carbon+Carbon Monoxide+carbon dioxide +water (+energy)
smoky flame (yellow)
what are the cons of incomplete combustion of alkenes x2
Why are alkenes a homologous series
carbon monoxide is poisonous
releases less energy than complete combustion
all have the same functional group
what is a functional group
why do alkenes react similarly
alkenes usually react by what type of reaction-explain
group of atoms in a molecule that determine how a molecule reacts.
they all have C=C double bond
addition reactions. the c=c double bond opens to leave a single bond- new atom added to each carbon
what is hydrogenation of an alkene
what is the product
what is needed for hydrogenation
addition of hydrogen
a saturated alkane
a nickel catalyst
High temp (150* c)
alkene+ halogen=
ethene + bromine=
in general what is the reaction of an alkene and halogen like-
dihaloalkane (Di because there are 2 halogen atoms)
dibromoethane
-quite rapid- no special conditions needed
what happens when bromine water is added to a saturated compound
What happens when an bromine water added to alkene- unsaturated
the orange bromine water stays orange, no reaction
(the bromine will add across the double bond) decolourises bromine water- colourless dihbromo compound is made
alkene + water (steam) =
How do you do this
what conditions are needed-
how is ethanol made industrially x4
alcohol
mix alkene w/ steam and pass over catalyst
-high temp(300*) and 70 atm and phosphoric acid catalyst
.
–mix ethene w/ steam. Pass over a catalyst. put mixture into condenser.
ethanol + water have higher bp than ethene, condense.
unreacted ethene recycled back into reactor.
ethanol purified from mixture by fractional distillation
what are polymers
What happens in addition polymerisation
‘
What conditions are needed for it
in addition polymerisation, the monomer will always be a ….
example of monomers
long chains of repeating units- monomers
Many small molecules- monomers join to form large molecule-polymer.
high pressure, a catalyst
alkene
- poly(ethene) or poly(propene) through addition polymerisation
what are plastics made of
carbon based polymers, monomers are often alkenes
what happens in addition polymerisation
the monomers originally have double c=c bond.
these unsaturated monomers (alkenes) open up the double bond and join together to form polymer chains
in addition polymers, why does the repeating unit have the same atoms as the monomer
How can you tell which is the monomer and which is the polymer
bcse no other molecule is formed
(the polymer is the only product)
monomer has C=C double bond
polymer has c-c bond
the monomers a polymer is made from affects the…… of the …… As there are many ………. there are many different ……
the monomers a polymer is made from affects the properties of a plastic. As there are many monomers there are many different plastics
How to draw displayed formula from of addition polymer from displayed formula of monomer - 4 steps
-how to go the other way round
how do you name a polymer
-draw the 2 alkene carbons, replace the C=C double bond with C-C bond
-add an extra empty bond to the side of each carbon
-fill in rest of bonds the way they are in the monomer.
-put brackets around the repeating bit- put n AFTER the brackets
—Draw out the repeating bi of the polymer
replace the C-C with C=C and get rid of the empty extra bonds
-poly(monomer) so if monomer is propene—- Poly(propene)
functional group of alcohols
general formula
first 4 alcohols
formulas- you MUST show the functional group
structural formulas
-O-H
CnH2nOH
methanol CH₃OH
ethanol C₂H₅OH CH₃CH₂OH
propanol C₃H₇OH CH₃CH₂CH₂OH
butanol C₄H₉OH CH₃CH₂CH₂CH₂OH
properties of first 4 alcohols
what happens to alcohols in air
Alcohol + O2=
flammable, soluble
undergo complete combustion
carbon dioxide + water +(energy)
what PH do alcohol solutions have
what happens to solubility as carbon no. increases
neutral,7
decreases
alcohol + sodium=
what can be seen
hydrogen + sodium(meth/eth/prop/but)oxide
hydrogen bubbles
alcohol + oxidising agent=
what happens to the alcohol
carboxylic acid + water
oxidised(to form carboxylic acid)
uses of alcohols, why
give an example
solvents- dissolve most things water can , + things water can’t eg hydrocarbons/oils/fats
-first 4 used as fuels- high flammability-
-ethanol used as fuel in spirit burners- burns cleanly, non smelly
how can ethanol be made by fermentation -3 steps
ideal conditions x3
why these conditions
-sugar solution mixed w/ yeast
-an enzyme in yeast converts sugars to ethanol- CO₂ also produced
-Ethanol produced is aqueous
37*C , slightly acidic conditions, anaerobic conditions( no O₂)
- enzyme in yeast works best to convert sugar to alcohol
-different ph/temp= enzymes denature/work slower
sugar solution mixed w/ yeast=
ethanol + carbon dioxide
functional group of carboxylic acids,
describe how this looks in displayed formula
What are the first 4 and formulas
-COOH ( double from c to o ) (single from c to o) (single from o to h)
—C=O
|
O-H
-Methanoic acid HCOOH
-ethanoic acid CH₃COOH
-propanoic acid C₂H₅COOH
-butanoic acid C₃H₇COOH
carboxylic acid + metal carbonate=
ethanoic acid + sodium carbonate=
propanoic acid + potassium carbonate=
what would u see -
salt (-ending in anoate) + water + carbon dioxide
sodium ethanoate + water + carbon dioxide
potassium propanoate + water + carbon dioxide
gas bubbles, CO₂ formed
What happens when a carboxylic acid dissolves in water
Describe pH of carboxylic acids
Carboxylic acid dissolved in water = what type of reaction
-in water, they are weak acids
-they ionise and release H+ ions
-don’t completely ionise, form weakly acidic solutions
-carboxylic acids have higher pH than strong acids eg hcl at same conc.
-reversible reaction
Ethanoic acid is dissolved in water, complete this equation
CH₃COOH (aq)
CH₃COOH (aq) ⇌ H+ (aq) + CH₃COO - (aq)
functional group of esters
ester you need to know
How does the functional group look
COO
ethyl ethanoate
C——O
||
O
(C=O)(C-O)
Alcohol + carboxylic acid=
what else is used in this reaction
How is ethyl ethanoate made
ester + water
acid catalyst eg (concetrated sulfuric acid)
ethanoic acid + ethanol AND acid catalyst
what happens in condensation polymerisation
why is it called condensation polymerisation
monomers with 2 of functional groups react and bond, making polymer chains.
for each new bond, small molecules eg water are lost- so the reaction is called condensation
the simplest polymers are produced from
How can polyester be made from condensation polymerisation
2 different monomers, with two of the same functional groups on each monomer.
ethanediol and hexanedioic acid polymerise to produce a polyester
condensation polymerisation to produce a polyester
HO- []-OH Ethanediol
HOOC- [] -COOH Hexanedioic acid
polymerise to produce:
(-O- [] - O-CO- []-CO-) n + 2nH₂O
A Polyester AND Water
what are the types of substances that polymerise together to get
a condensation polymer
a diol + a dicarboxylic acid= condensation polymer + water
(OH group) (COOH group) = (COO group) + (H2O)
number of types of monomers
in addition Vs condensation polymerisation
ADDITION-
only one monomer type containing C=C bond
CONDENSATION-
2 monomer types- each containing 2 of the same functional groups
OR…..
1 monomer type with different functional groups
number of products
in addition Vs condensation polymerisation
ADDITION-
only one product formed
CONDENSATION-
Two types of product- the polymer and small molecule (eg water)
functional groups involved
in addition Vs condensation polymerisation
ADDITION-
alkene c=c
CONDENSATION-
2 reactive groups on each monomer
alkene + what = alcohol
how can more of the alcohol be made
what is special about this reaction
steam
unreacted alkene and steam are passed back over catalyst
it is reversible
-what are the 2 different functional groups in 1 molecule of amino acid
-what type of polymerisation do amino acids undergo
-what is produced in this
c=o-o-h carboxylic acid group
H2N- amine group
-condensation
-polypeptide
-water
what is the structure of amino acid glycine
chemical formula for what glycine polymerises to produce
google it and remember it pls
(-HNCH₂CO-)n and n H₂O.
what happens when 2 glycines - (amino acids) react
-what if many reacted
-the oh from carboxylic acid group and a h from amine group react to make water
-then o=c and n-h join together
-this is called a peptide
-many amino acids joined tgther like this makes a polypeptide which is the polymer
-amino acids are the monomers
why is a polypeptide called this
-what is a protien
made from the same type amino acids
-when different amino acids combine into the same chain
why is a polypeptide called this
-what is a protien
made from the same type amino acids
-when different amino acids combine into the same chain
What is dna
what does it do
-most dna molecules are made up of-
a large molecule essential for life
-encodes genetic instructions for the development and functioning of living organisms and viruses
-2 polymer chains , made from 4 different monomers- nucleotides
-in form of double helix
naturally occuring polymers and what monomers they are made of x4
protien- amino acids
starch-glucose
cellulose-glucose
dna-nucleotides
alkene + hydrogen=
alkene + water=
alkene + halogen=
acid + carbonate=
Alkane
Alcohol
diHaloAlkane
Salt + Co2 + H2O
uses of methanol
-chemical feedstock- meth=mouth—>feedstock
-toxic- used in methylated spirits/disinfectants to stop ppl drinking them
meth=not good=toxic
uses of ethanol
main alcohol in drinks-
mixed w/ petrol for use as fuel
-ethan drinking alcohol at petrol station
uses of propanol + butanol
solvent +fuel
how is a polymer formed from its monomers in addition polymerisation
many monomers
join
to form a long chain
no other substance
c=c break so the monomer can join to another
needs catalysts, pressure, heat or UV light
Why does a thermosoftening polymer melt when heated
It has intermolecular forces between the chains
Which are weak
Which needs little energy to overcome
ethanoic acid + sodium carbonate=
sodium ethanoate + water + carbon dioxide
metal + acid=
sodium + ethanoic acid=
salt + hydrogen
sodium ethanoate + hydrogen
what compound dissolves in water to give a neutral solution
alcohol
why is alcohol able to soluble in water
due to oh- group
Solutions of ethanoic acid and hydrochloric acid have different pH values at the same concentration because:
Ethanoic acid only partially ionises
There is a lower concentration of hydrogen ions
the pH value is higher than that of HCl
how could you tell from an equation that the acid is weak-
the reversible reaction arrow
conditions needed for making ethanol from sugar solution
Fermentation;
glucose
Add yeast
anaerobic conditions
Warm conditions (20-45*)
-what happens in fermentation to produce ethanol
-why does temp need to be warm
during fermentation;
C6H12O6 → 2CO2+ 2C2H5OH
-yeast respire anaerobically
-provide the enzymes to break down the glucose to ethanol + co2
- if the reaction is too cold, r.o.r very slow
-too hot - enzymes denature
conditions needed to convert ethene to ethanol- hydrogentation
Steam;
High temperature;(300- 330)
High pressure;( 60 and 70 atm)
Acidcatalyst;phosphoric acid
-the ethene comes from non renewable crude oil
there are 3 ADDITION reactions for alkenes-
ALKENE+
halogen=
hydrogen=
steam=
.
dihaloalkane
-alkane
-alcohol
how are carboxylic acids formed-
alcohol OXIDISED with an oxidising agent presented in equation as [O]
what is esterification-
ethanoic acid + ethanol = ethyl ethanoate + water
(acid +alcohol= ester + water)
ethanoic acid + alkali = salt and water
what type of reaction is this
neutralisation
what catalyst is needed in esterification
acid catalyst
compare structure and reactions of propene and propane-
Structure and bonding
* Both hydrocarbons
* three carbon atoms
* Propane- 8 h atoms
* propene -6 h atoms
* Both covalent
* Both have C—H bonds
* Both small molecules
Reactions
* Both react w/ oxygen -complete combustion
* and make H20 + CO2
* Both react w/ oxygen - incomplete combustion reactions
* and make h20, co, co2
* Incomplete combustion more likely w/ propene
* Propene decolourises bromine water
* (But) propane does not decolourise bromine water
* Propene is more reactive (than propane)
* Propene can react with hydrogen
* Propene can react with water
* Propene can react with halogens
* Propene can undergo addition reactions
* Propene can polymerise
