2.5 - Crude oil, fuels and organic chemistry Flashcards
What is crude oil?
A finite resource found in rocks, formed over millions of years from the remains of simple marine organisms
It contains a complex mixture of hydrocarbons
What are the processes in the fractional distillation of crude oil?
Note: Crude oil is evaporated inside a blast furnace before entering
The mixture is put into the fractionating column at the bottom and heated.
The hydrocarbons evaporate and rise up the column.
As the hydrocarbons rise, they eventually reach a fraction which is cool enough for them to condense back into a liquid.
The mixture left at the bottom, which does not evaporate is called bitumen
What are fractions in fractional distilation?
Fractions contain mixtures of hydrocarbons (alkanes) with similar boiling point
As you go up the fractionating column, the hydrocarbons have? Talk about: Chain length Boiling point Volatility Flammability Colour
smaller chain lengths lower boiling points more volatility (easy to evaporate) higher flammability (they ignite more easily and burn more cleanly) lighter colour (the bottom fraction is black, the middle fractions range from brown to yellow and the fraction at the top is colourless)
A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is ___ (hot/cool) at the bottom and ___ (hot/cool) at the top. Substances with high boiling points condense at the ____ (top/bottom) and substances with lower boiling points condense on the way to the ___ (top/bottom)
Hot
Cool
Bottom
Top
What is the economic importance of the oil industry?
Oil companies set the price of oil so there is an influence globally on the economy - it can be harder for poorer countries to buy oil.
War or internal crisis within a country that produces oil can effect the flow of oil to other countries which they sell to.
What is the political importance of the oil industry?
Countries that are large producers of oil can essentially cut off oil supplies to other countries.
This is used as a political tool
What are the environmental impacts of the oil industry?
Burring fossil fuels releases large amounts of carbon dioxide, a greenhouse gas, into the atmosphere, contributing to global warming and climate change
The building of power stations and the process of drilling for oil causes damage to the landscape and loss of habitat
Oil spillages into the ocean result in the deaths of marine life and birds and are often dealt with setting them alight
What is cracking used for?
Allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules.
In cracking, fractions containing large hydrocarbon molecules are heated to vaporise them. They are then:
heated to _____
passed over a catalyst of ____ or ____
600-700°C
silica, alumina
What are the combustion reactions of hydrocarbons?
When hydrocarbons burn in plenty of oxygen it will combust as follows: hydrocarbon + oxygen → carbon dioxide + water
What is the fire triangle?
A symbol that contains 3 things needed for a fire to burn: oxygen, fuel and heat
Removing any of these will cause the fire to stop burning
What method do you use to remove oxygen, heat and fuel from a fire? What is the type of fire?
Oxygen - Fire blanket, CO2 extinguisher
Oil fires, chip-pan fires, electrical fires
Heat - Water
House fires, wood fires, paper fires
Fuel - Firebreak
Forest fires
What is calorimetry?
An experiment technique used to workout the energy released when burning a fuel
What is the method of Calorimetry?
1) A know volume of water is added to a calorimeter and the temp is recorded
2) A known mass of fuel is burnt beneath the calorimeter
3) The maximum temperature of the water and the final mass of the fuel is recorded
When comparing different fuels, it is important to carry out a fair test. Several variables should be kept constant. They include:
1) the volume of water used
2) the starting temperature of the water
3) the temperature increase
4) the distance of the flame from the calorimeter
What is the combustion reaction of hydrogen and what are its uses?
Hydrogen burns in oxygen and forms water
Hydrogen is used as a fuel in rockets and some cars
What are the advantages of using hydrogen as a fuel?
No greenhouse gases are produced in the combustion of hydrogen
An alternative fuel option as current fuels are running out
What are the disadvantages of using hydrogen as a fuel?
Hydrogen is extremely flammable
Most of hydrogen produced comes from fossil fuels or electrolysis so it still has a negative impact on the environment.
Hard to store and transport - mist be cooled to very low temperatures so it liquefies for storage and transport.
What are the products of hydrocarbon cracking?
Alkanes and unsaturated hydrocarbons called alkenes
Alkenes are monomers that are used to make plastics
What is the general formula of alkanes?
CnH2n+2
What is the general formula of alkenes?
CnH2n
What are some examples of simple alkanes? List down their name, molecular and structural formulas.
Methane, CH4, CH4
Ethane, C2 H6, CH3CH3
Propane, C3H8, CH3CH2CH3
Butane, C4H10,CH3,CH2,CH2,CH3
What are some examples of simple alkenes? List down their name, molecular and structural formulas.
Ethene, C2H4, CH2=CH2
Propene, C3H6, CH2=CHCH3
Butene, C4H8, CH2=CHCH2CH3
Alkanes are _____ (saturated, unsaturated) hydrocarbons. This means that their carbon atoms are joined to each other by single bonds. This makes them relatively unreactive, apart from their reaction with oxygen in the air – which we call burning or combustion
saturated
What is isomerism?
When two compounds have the sae molecular formula ( same number and type of each atom) but their structures differ in some way
Alkenes are ____ (saturated, unsaturated) meaning they contain a double bond. This bond is why the alkenes are more reactive than the alkanes.
unsaturated
What is isomerism in alkanes?
The main carbon chain length differs but the molecule still has the same number of carbon atoms
What is isomerism in alkenes?
The position of the double bond in the molecules can differ but the molecular structure stays the same
The presence of the C=C double bond allows alkenes to react in ways that alkanes cannot. This allows us to distinguish alkenes from alkanes using a simple chemical test. What is the test for alkenes?
Bromine water is an orange solution of bromine. It becomes colourless when it is shaken with an alkene. Alkenes can decolourise bromine water, but alkanes cannot. (Addition reaction)
What are addition reactions?
Reactions in which two or more molecules combine to form a larger one with no other products
What are some other addition reactions of alkenes?
.
Hydrogen can be added to a C=C double bond. This has the effect of ‘saturating’ the molecule, and will turn an alkene into an alkane. For example: C2H4 + H2 → C2H6.
If steam (H2O) is added to an alkene, an alcohol is made. For example: C2H4 + H2O → C2H5O.
Name the molecules up to 5 carbons long?
1 - meth 2 - eth 3 - prop 4 - but 5 - pent
What kind of bonds do Alkanes, Alkenes and Alcohols have? Give examples.
Alkanes – only single bonds naming: methane, ethane etc Alkenes – contain a C=C naming: ethene, propene etc Alcohols – contain an –OH naming: butanol, propanol etc
How do you name more complex alkanes and alkenes?
Locate the longest continuous linear chain of carbon atoms
Number the carbon atoms from the end closest to a functional group or branch point
Alphabetically list the functional groups attached to the carbon chain and state the carbon number the group is attached to
For double bonds, count the position of the double bond by counting bonds not carbons.
What is addition polymerisation?
Alkenes can be used to make polymers.
Polymers are large molecules made up of repeating units called monomers.
Alkenes can be polymerised because they have double bonds that open up to connect to other alkene monomers in a chain
E.g. polyethene is formed from ethene monomers
How can the method of polymerisation can be summarised?
1) Monomers have their double bonds broken
2) Large numbers of monomer molecules will join together
3) It forms a long chain called a polymer
Alkenes can act as monomers because they are unsaturated. What does unsaturated mean?
An unsaturated compound compound contains at least one double or triple bond
What are the properties and uses of polyethene?
Low density, waterproof
Plastic bags
What are the properties and uses of poly(propene)?
Strong/colourful
Ropes, textiles
What are the properties and uses of poly(tetrafluoroethene) (PTFE)?
Non stick
Coating for frying pans
What are the properties and uses of poly(chloroethene) (PVC)?
Low density and doesn’t corrode
Water pipes, electrical wires
What are some uses of modern polymers?
new packaging materials
waterproof coatings for fabrics (eg for outdoor clothing)
fillings for teeth
dressings for cuts
hydrogels (eg for soft contact lenses and disposable nappy liners)
smart materials (eg shape memory polymers for shrink-wrap packaging)
What are the environmental issues relating to disposal of plastic bags?
Plastics are non - biodegradable
Increasing pressure on landfill sites for waste disposal
What are the 3 methods for disposing plastics?
1) Landfill sites
2) Incineration disposal - however this releases CO2, a greenhouse gas
3) Recycling - this manages the other issues of disposal, provides jobs and helps preserve the non-renewable source of crude oil.
What is the general formula of alcohol?
Cn H2n+1 OH
Alcohols all contain the functional group ___
OH-
How is ethanol produced?
The fermentation of sugar using yeast - the enzymes in yeast catalyse the reaction
Glucose –> Ethanol + Carbon Dioxide
What are the uses of ethanol?
Found in alcoholic drinks
As a solvent - it dissolves a large number of substances easily
As a fuel
What are the social impacts of alcoholic drinks?
Bad for health and causes a number of illnesses including liver diseases, cancers and cardiovascular problems
Can increase the number of violent fights and other crimes
What are the economic impacts of alcoholic drinks?
Taxation of alcoholic drinks and alcohol export out of the UK bring money to the economy
The alcohol industry provides jobs
Cost the economy due to healthcare and police costs from alcohol-related issues.
What are the advantages of using ethanol as a fuel?
Carbon neutral fuel - no net addition of CO2 into the atmosphere
Good fuel alternative for countries without their own crude oil supply
Renewable source - made from sugar cane
What are the disadvantages of using bioethanol as a fuel?
Energy is needed in growing sugar canes, distillation and transportation of ethanol which will require burning of fossil fuels so it will still cause global warming
Engines must be altered before they can use bioethanol as a fuel.
Can causes deforestation to provide land for growing sugar cane.
Some areas of the world are not hot enough or have enough light hours in the day to be able to completely switch to biofuel
Using food as fuel can increase food prices
What is the test for alcohol?
1) Add a few drops of sulfuric acid and potassium dichromate solution to the sample
2) Gently heat
3) If alcohol is present the solution will change from orange to green
How do you name alcohols?
The suffix -ol which is preceded by the number of the carbon the hydroxyl (OH) functional group is attached to.
If there are multiple alcohol functional groups (OH’s) the suffix becomes - diol, -triol, -tetrol
What is the microbial oxidation of ethanol?
When ethanol is oxidised it forms ethanoic acid, a carboxylic acid which has the functional group -COOH
This oxidation can be carried out by microbes
An oxygen atom is gained and hydrogen atoms are reduced
What is infrared spectroscopy?
An experimental technique that can be used to work out the structure of a compound or molecule.
When infrared light is shone at a compound, its bonds absorbs some of the infrared light.
Different bonds absorb at different frequencies of infrared light.
An infrared spectrum, which contains peaks corresponding to different bond types, is produced.
By identifying different peaks, functional groups in the compound can be identified.
