Organic Chemsitry Flashcards
what is a homologous series
a group of organic compounds which share some characteristics
What characteristics do a homologous series share
- each compound has same functional group, and same general formula
- all do the same chemical reactions
- a gradual change in physical properties like boiling points, viscosity
- differ from previous member by a CH2 group
how are alkenes arranged
They have a double carbon bond
how are alcohols arranged
R (rest of molecule) -OH
way of remembering how many carbon atoms are in a molecules
Monkeys - meth
Eat - eth
Peeled - prop
Bananas - but
Properly - pent
what are the threes endings and what do they mean
ane -means it belongs to the alkanes/ homologous series
ene - alkene
anol- alcohol
what are hydrocarbons and give and example
compounds that only contain C and H atoms
General formula of alkanes
CnH2n+2
how are alkanes different and similar
Different - physical properties and differ by CH2
Similar - same functional group, general formula and chemical proeprties
Molecular formula and state at room temp of methane
CH4 - gas
Molecular formula and state at room temp of Ethane
C2H6 - gas
Molecular formula and state at room temp of propane
C3H8 - gas
Molecular formula and state at room temp of butane
C4H10 - gas
Molecular formula and state at room temp of pentane
C5H12 - liquid
Molecular formula and state at room temp of hexane
C6H12 - liquid
What are isomers
Compounds with the same molecular formula but different structures so hence their properties can differ
Which isomer of pentane would you expect to have the lowest boiling point
Dimethyl propene - as molecules aren’t able to line up closely together so weaker intermolecular forces
What is formed when complete combustion happens with an alkane and oxygen
Carbon dioxide and water are formed
Why are the shorter alkanes used as fuels
They react easily with oxygen
Why are alkanes quite interactive
Have many single strong covalent bonds
What do i also need to revise
STRUCTURES OF BRANCHES ALKANES AND ISOMERS ON PAGES 9 AND 10
what determines the boiling point of alkanes
the strength of the intermolecular forces
as the molecules of alkanes get larger what happens to their boiling points and intermolecular forces
the boiling points increase due to the stronger intermolecular forces
how can crude oil be separated into a number of different liquids
by fractional distillation
what is crude oil?
Crude oil is a fossil fuel that is formed from the remains of ancient plants and animals that have been buried and subjected to high pressure and heat over millions of years. Crude oil is a complex mixture of hydrocarbons, which are molecules made up of hydrogen and carbon atoms.
as the boiling point of the fractions increases what happens to the
a) appearance
b) ease of lighting
c) smokiness of the flame
d) the viscosity
a) they become darker in colour
b) they become harder to light/less reactive
c) they burn with a smokier flame
d) they get more viscous/ thicker and more treacle like
as you go up the fractionating column what are the the qualities of the fractions in comparison to the bottom of the column
low boiling point, low density, small molecules, light in colour, runny
high boiling point, dark in colour, hard to light, thick (if a liquid), large molecules
refinery gases bpt, number of carbon atoms, and uses
20 degrees, 1-4, fuel for domestic heating/cooking
petrol/gasoline bpt, number of carbon atoms, and uses
120 degrees, 5-10, fuel for cars
kerosine bpt, number of carbon atoms, and uses
170 degrees, 10-14, fuel for aircraft
diesel bpt, number of carbon atoms, and uses
270 degrees, 14-20, fuel for (some) cars and for trains
fuel oil bpt, number of carbon atoms, and uses
400 degrees, 20-50, fuel for ships and power stations
bitumen bpt, number of carbon atoms, and uses
more than 400 degrees, more than 50, for roads and roofing - is a solid at room temperature
4 steps of fractional distillation:
- heated crude ? enters near the bottom of a tall
? column which is ? at the bottom and gets cooler towards the ?
- vapours from the ? rise through the column
- vapours condense when the ? of the column is cool ?
- ? are led out of the column at different ?
- oil, fractionating, hot, top
- oil
- temperature, enough
- liquids/fractions, heights
3 differences between alkanes and alkenes
alkenes contain a C=C bond, while alkanes do not
they have different functional groups
alkenes are UNsaturated hydrocarbons, while alkanes are saturated hydrocarbons
test to show the presence of a double bond in an alkene and name
shake an alkene with orange bromine water and it should turn colourless/decolourise
what happens to the alkene when shaken with bromine water
the C=C bond breaks open and the Br2 molecule joins to the alkene to make 1 molecule that only has single bonds
revisit which pages?
27 + 28
WHAT TWO THINGS ARE NEEDED FOR CRACKING?
a catalyst and heat
which fuels do we have surplus of in comparison to fuels we have deficit of
have lots of fuel oil and long chain oils and paraffin, but need more petrol and diesel
how does cracking work?
some of the fuels which are provided in excess that contain long chain alkanes like fuel oil are broken down into shorter chain products, by thermal decomposition.
what is the general cracking equation?
Longer alkane —> shorter alkane + short chain alkenes
what are the two catalysts’ formulae and names in cracking
Silica/ SiO2 and Alumina/ Al2O3
Example of Dodecane getting cracked (with two relatively small alkenes and alkanes)
C12H26 —> C6H12 +C6H14
3 main uses for cracking products
Alkanes can be made into shorter chain alkanes which are more useful eg gasolene
Alkenes are also useful and can be made into :
1. Polymers and plastics eg polyethene
2. Ethanol from ethene
What is medicinal paraffin and how can you crack it?
A mixture of hydrocarbon molecules which can be cracked by heating it and passing the vapour over hot pieces of pot
Why is a valve needed at the end of a delivery tube in laboratory cracking?
To stop the water being pushed back into the boiling tube and breaking the tube
What are polymers and how were they formed?
Long molecules with up to many thousands of carbon atoms arranged in a long chain and are formed by joining small molecules called monomers
how can general equation of polymers and what they stand for
-[M]n-
n is the repeat unit of unknown length/large number
M is a monomer
what type of polymerisation do alkenes undergo and why can they do this?
addition polymerization, as they contain a C=C double bond
what page is it helpful to go back to in booklet?
31 and 32
what is used to coat copper wiring in electrical devices?
polychloroethene (PVC) as it’s a great electrical insulator and very corrosion resistant
what is used to make fizzy drink bottles?
polyethaneterephthalate (PET), because it’s very flexible- and transparent so easy to ‘blow mould’
what is used to coat frying pans?
polytetrafluoroethene (PTFE) because it’s low friction - non stick
what is used for the lens for spectacles?
polymethylmethacrylate (acrylic) as it’s highly transparent
what is used for the fabric for carpets?
polypropene as it’s easy to colour
many addition polymers are non biodegradable- what does this mean and why isn’t it eco friendly?
don’t break down via natural methods, therefore we end up with a build up of non disposable plastics
3 main methods of plastic disposal?
Burning, landfill, recycling
Pros and cons of burning
Pros : - can generate energy to heat homes and electricity as well
- disappears into a small pile of ash
- less storage needed
Cons: - released CO2 emissions
- toxic gases released
Pros and cons of landfill
Pros: - cheap
- easy to do
Cons: - land used up
- eyesore
- plastics stay for many years
- destroys habitats/ ecosystems
Pros and cons of recycling
Pros: - preserves a finite resource of crude oil
- cuts amount of rubbish sent to landfill
- no need for so many oil wells (which destroy habitats)
- less energy needed
Cons: - costs money
- difficult to sort
- Labour intensive
- collection increases transport and so CO2 emission also
Functional group of alcohols
R-OH
General formula of the alcohols
CnH2n+1OH
The process of ? involves adding some raw ? such as grapes for ?, malted ? for beer, and sugar ? or maize for ? or just plain ?. They are then mixed with ? and water and kept at just above room ? so around 20-30 ?. The yeast also contains ? which are biological ?.
fermentation, materials, wine, barley, cane, fuel, sugar, yeast, temperature, degrees, enzymes, catalysts
Two conditions of yeast fermentations
- aerobic - if there’s plenty of O2 the enzymes will break down sugar to CO2 and H2O
- anaerobic - if there’s no oxygen, the yeast catalyses the breakdown of sugar into ethanol and CO2.
in the anaerobic respiration of yeast why is CO2 allowed to escape but why is air not allowed in?
CO2 needs to escape so it doesn’t poison the yeast, but air isn’t allowed so that the yeast continues to produce ethanol
Ethanol and CO2 can be used directly if the drink is wine or beer but what happens if something stronger is required eg a spirit?
Due to the concentration is higher, or the ethanol needs to be used as a solvent/fuel - the ethanol is separated from the reaction mixture by fractional distillation
Fractional distillation is used in ethanol when the concentration of alcohol is above what percentage?
15%
What is the functional group of carboxylic acid and an example of an acid?
COOH, Ethanoic acid - CH3COOH, or C2H4O2
How is ethanol dehydrated?
It’s heated in the presence of an Al2O3 catalyst, which then vapourises and forms water and ethene - so loses OH and H from one adjacent carbon
what is formed if propan - 1 - ol is dehydrated
propene + water
what is formed if butan - 1 - ol is dehydrated
but-1-ene + water
what is formed if butan - 2 - ol is dehydrated
but-1-ene + water
but-2-ene + water
how to remember formula for carboxylic acids?
the rule for carbon and hydrogen is the same as the alkenes and then there is always 2 oxygens
what happens to the H atom at the end of the COOH base
it is lost when added to an alkali/base
difference between molecular formula and displayed formula?
molecular is how many molecules of each atom make up the substance, whereas displayed formula is the substance displayed with all its molecules and its different bonds (a drawing)
what happens when ethanoic acid is tested/reacted with
a) universal indicator
b) calcium carbonate
c) magnesium
a) it turns orange/ light red as it’s a weak acid
b) there is fizzing - as co2 is given off
c) fizzing, as hydrogen is given off
what happens when the mixture of ethanol, ethanoic acid and conc. sulphuric acid are mixed and then put in a water bath AND added to half a beaker of sodium carbonate solution
the mixture fizzes in the beaker, and gives off a smell like nail varnish remover - this is called an esther
chemical and ionic equation for ethanoic acid and magnesium
2CH3COOH + Mg –> (CH3COO)2Mg + H2
2H+ + Mg –> Mg2+ + H2
when an alcohol is dehydrated, what are the two products?
an alkene and water
what are the two ions for ethanoic acid
CH3COO- and H+
how are carboxylic acids formed?
By oxidising alcohols
what happens when propene is heated with a catalyst and what is the polymer called?!
addition polymerisation, polypropene
test for carboxylic acid
fizzes with sodium carbonate
how is a polyester formed?
by reacting a dicarboxylic acid (2 carboxylic acids) and a diol (two alcohols) together
ways to reduce carbon and carbon dioxide problems
use alternative energy sources eg wind or solar
How are nitrogen oxides formed, what do they cause and ways to reduce?
react with oxygen in car engines at high temps and pressures
cause acid rain
use catalytic converters
Sulfur dioxide info
Is formed by burning fossil fuels as they contain some sulphur
Cause acid rain/ sulphuric acid droplets
Can filter out from power stations by capturing with limestone
Problems with unburned fuel
Come from car engines, the unburned fuel
Full of carcinogens, causes photochemical smog
How is carbon monoxide damaging and ways to manage
Toxic gas which stops blood carrying oxygen around body, fit with catalytic converters
Carbon potential problems and how it’s formed?
Formed in incomplete combustion of fossil fuels eg wood burners or car engines
Global dimming - blocks sunlight, causes breathing problems and can be carcinogenic
Difference between a chemical and fuel cell
Chemical cell produces a voltage until one of the reactants has been used up compared to a fuel cell that’s supplied with oxygen and fuel to efficiently release energy
what is the product of a hydrogen oxygen fuel cell
Water - which is a non pollutant
Pros of fuel cells vs conventional cells
Fuel cells :
No pollutants
Constant voltage
No need to recharge
Conventional cells :
All the chemicals needed are inside the cell
Cons of fuel cells vs conventional cells
Fuel cells :
Have to be supplied with fuel and oxygen
Conventional cells :
Voltage is only produced until one of the reactants is used up
Batteries contain many toxic chemicals which need a safe disposal
Fuel cell make up
Has a current which runs through the electrolyte - on the left has fuel in and the anode and on the right has air in and the cathode.
On the left excess fuel leaves and on the right unused gases leave out
