Crude Oil, Fuels and Organic Chemistry Flashcards
What is organic chemistry?
Chemistry of carbon based compounds
What is crude oil?
Crude oil is a mixture of hydrocarbons formed from the remains of simple marine organisms over millions of years.
What does fractional distillation do?
Fractional distillation separates a mixture into a number of different parts, called fractions.
A fraction of crude oil is a mixture of chemicals in the crude oil that have similar boiling points
Explain the structure of a distillation collumn?
The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
What are the different sections for the fuels in the distillation collumn?
Petroleum gas (domestic) Petrol (fuels) Naptha (chemicals) Kerosene (aircraft) Diesel (fuel) Lubricating oil (machinery) Fuel oil (fuel) Bitumen (roads)
What is the acronym for remembering the order of fuels?
Petty People Never Know Donkeys Love Finding Bananas
Features of small molecules?
- Low boiling point
- Very Volatile
- Flow easily
- Ignite easily
Features of large molecules?
- High boiling point
- Not very volatile
- Does not flow easily
- Does not ignite easily
Temperature at bottom of collumn?
350c
Temperature at top of collumn?
25c
As you go up the collumn, the hydrocarbons have…..?
- 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)
What is natural gas mainly composed of?
Methane, it is used in domestic practices
How was coal formed?
The remains of ancient forests
How does coal contribute to acid rain?
Coal contains sulphur
3 points of economic importance regarding crude oils?
- The price of crude oil is controlled by oil companies, which means they have a great deal of influence on the global economy, and poorer countries can easily lose control of their own economy.
- Countries that produce oil for other countries hold a great deal of political power as they can essentially ‘cut off’ other countries from the crude oil supply over any political disagreements.
- War or a political crisis in an oil-producing country can restrict crude oil supplies, which can have a major impact on the global economy.
3 points of environmental importance regarding crude oils?
- Burning fossil fuels releases carbon dioxide into the atmosphere. This is widely accepted as a major contributor to global warming.
- Oil spillages can have a disastrous effect on the local environment, killing off thousands of animals such as fish and sea birds, and require a great deal of effort to clean up.
- Oil refineries and oil-fired power stations take up a lot of land and so destroy potential wildlife habitats and spoil the countryside. However, this problem is the same for any industrial site and so is not just a problem for the oil industry.
What is cracking?
Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are heated to vaporise them.
How is cracking carried out and what happens in this process?
- heated to 600-700°C
- passed over a catalyst of silica or alumina
These processes break covalent bonds in the molecules, causing thermal decomposition reactions. Cracking produces smaller alkanes and alkenes.
What does the cracking of decane give you?
Octane + ethene
C10H22 → C8H18 + C2H4
What are polymers?
A large molecule formed from many identical smaller molecules called monomers
Is combustion exothermic or endothermic?
Exothermic
What is combustion?
A fuel burning in oxygen
What percentage of the air is oxygen?
21%
What happens when hydrocarbons combust?
- the carbon oxidises to carbon dioxide
- the hydrogen oxidises to water (remember that water, H2O, is an oxide of hydrogen)
What is the formula for complete combustion?
hydrocarbon + oxygen = carbon dioxide + water
What is the equation for the complete combustion of propane?
propane + oxygen → carbon dioxide + water
C3H8 + 5O2 → 3CO2 + 4H2O
What is the equation for complete combustion of methane?
methane + oxygen → carbon dioxide + water
CH4 + 2O2 → CO2 + 2H2O
What is the equation for the combustion of ethanol?
ethanol + oxygen → carbon dioxide + water
C2H5OH + 3O2 → 2CO2 + 3H2O
What does the fire triangle show?
the three things that are required for a fire to burn
What is needed for a fire to burn?
Oxygen
Heat
Fuel
How can we remove oxygen from a fire?
Fire blanket
CO2 extinguisher
Oil fires, chip-pan fires, electrical fires
How can we remove heat from a fire?
Water
House fires, wood fires, paper fires
How can we remove fuel from a fire?
Firebreak
Forest fires
What 4 ways can energy be released in chemical reactions?
Light, sound or electrical energy, heat
Equipment needed in the calorimetry experiment?
- thermometre
- calorimeter
- water
- spirit burner
What is the calorimetry method?
- Cold water is measured into a copper calorimeter – a small metal can.
- The starting temperature of the water is recorded.
- The water is heated using the flame from the burning fuel.
- The final temperature of the water is recorded.
The spirit burner containing the fuel is usually weighed before and after the experiment so that the mass of the fuel burned can be found.
What 4 variables should stay the same in the calorimetry experiment?
- the volume of water used
- the starting temperature of the water
- the temperature increase
- the distance of the flame from the calorimeter
What is the biggest source of error in a calorimetry experiement?
- unwanted heat loss to the surroundings
- this can be reduced by insulating the sides of the calorimeter and adding a lid
What is the equation for energy released per gram of fuel?
Energy given out = mass of water × 4.2 × temperature change
What is energy measured in?
joules, J
What is mass of water measured in?
grams - 1cm3 = 1g
Why is 4.2 used?
4.2 is the specific heat capacity of water, J/g°C
Equation for temperature change?
Temperature change = temperature of water after heating – temperature of water before heating
What is hydrogen used for?
- Fuel for rockets
- fuel for hydrogen fuel cells in cars
Equation for the combustion of hydrogen?
hydrogen + oxygen → water
2H2 + O2 → 2H2O
The color of a hydrogen flame?
Almost colourless
Why do people see hydrogen as clean?
- no carbon dioxide is released when it burns
- replace fossil fuels that are causing global warming
What are the 3 issues with using hydrogen as fuel?
- most of it is still obtained from fossil fuels
- it is highly flammable (more dangerous than oil-based fuels)
- storage = very expensive (-250*)
what is meant by a homologous series?
they have similar chemical properties to each other and they have trends in physical properties
What is the formula for an alkane?
CnH2n+2
Molecular formula of butane?
c4h10
What is meant by alkanes being saturated?
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
What is isomerism?
This means that their atoms can be arranged differently to make slightly different compounds with different properties
What are the 2 isomers of c4H10
Butane and methylpropane
What are alkenes?
Hydrocarbons that contain a carbon-carbon double bond
What is the general formula for alkenes?
CnH2n
What is meant by butene having 2 straight chained isomers?
but-1-ene (double bond with the first carbon)
but-2-ene (double bond with the second carbon)
What is meant by alkenes being unsaturated?
they contain a double bond. This bond is why the alkenes are more reactive than the alkanes.
How do you test for alkenes?
Bromine water - it becomes colorless when shaken with an alkene
(addition reaction)
Addition reaction, chemical formula of ethene plus bromine?
ethene + bromine → 1,2-dibromoethane
C2H4 + Br2 → C2H4Br2
CH2=CH2 + Br–Br → CH2BrCH2Br
How can you saturate a molecule?
Hydrogen can be added to a C=C double bond.
will turn an alkene into an alkane. For example: C2H4 + H2 → C2H6.
What happens when H2O is added to an alkene?
Alcohol is made
Number of carbons in meth?
1
Number of carbons in eth?
2
Number of carbons in prop?
3
Number of carbons in but/
4
Number of carbons in pent?
5
How can you name organic compounds?
Select the longest unbranched chain of carbons. The chain may not be drawn ‘straight’.
Number the chain from the end where branching starts first – or the end where the functional group is.
List the branching groups and functional groups alphabetically, including a number denoting which carbon in the chain they are attached to.
What can alkenes be used to make?
Polymers
What are polymers?
Polymers are very large molecules made when many smaller, reactive molecules join together, end to end. The smaller molecules are called monomers.
What are lots of monomer molecules known as?
A polymer molecule
What is the process of addition polymers?
monomers have their double bonds broken
large numbers of monomer molecules will join together
it forms a long chain called a polymer
What does ethene polymerise into?
poly(ethene), polythene
What does propene polymerise into?
poly(propene)
polypropylene
What does chloroethene polymerise into/
poly(chloroethene)
PVC
What does tetrafluoroethene polymerise into?
poly(tetrafluorothene)
PTFE or Teflon
How do you draw polymerisation?
change the double bond in the monomer to a single bond in the repeat unit
add a bond to each end of the repeat unit
draw brackets around the repeating unit so that the brackets go through the middle of the bonds at the end
put the letter n in subscript after the brackets (n represents a very large number of the repeating unit)
What are the properties of polyethene?
Plastic bags
Low density, waterproof
What are the properties of polypropene?
Ropes
Strong, colourful
What are the properties of polytetrafluoroethene?
Coating for frying pans
Non-stick
What are the properties of poly(chloroethene)?
Water pipes
Low density
Does not corrode
What can modern polymers be used for?
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 with polymers?
- very unreactive
- non-biodegradable
The benefits of recycling polymers?
Less plastic goes to landfill, reducing pollution and making current landfill sites last longer.
Less crude oil is needed to produce new plastics. This conserves crude oil which is a finite resource that will eventually run out.
Recycling plastic requires less energy than making new plastic. This lowers costs and reduces greenhouse gas emissions.
What is the general formula for alcohols?
CnH2n+1OH
What do the names of alcohols end with?
‘ols’
What are the first three alcohols and what are they used for?
The first three alcohols in the homologous series are methanol, ethanol and propanol. They are highly flammable, making them useful as fuels. They are also used as solvents in marker pens, medicines, and cosmetics (such as deodorants and perfumes).
How can ethanol be made?
Fermentation
What happens during fermentation?
sugar (glucose) from plant material is converted into ethanol and carbon dioxide. This typically takes place at temperatures of around 30°C.
The enzymes found in single-celled fungi (yeast) are the natural catalysts that can make this process happen:
C6H12O6 2C2H5OH + 2CO2
Health issues regarding alcohols?
Alcohol is a direct cause of around 10 per cent of diseases and deaths in the UK. The diseases directly linked to alcohol abuse include a number of different cancers, high blood pressure, cirrhosis of the liver and depression.
The number of deaths directly linked to alcohol in the UK is close to 9,000 each year.
It is the third most dangerous lifestyle factor, after smoking and obesity.
What are the economic facts regarding alcohols?
Alcohol misuse in the UK is estimated to cost over £21 billion per year as a result of healthcare costs, police costs and lost productivity due to missing work.
The export of alcoholic drinks contributes just over £6 billion to the annual UK economy.
The drinks industry in the UK employs around 650,000 people directly, and supports over 1 million more jobs in the wider economy.
Tax on alcoholic drink sales brings in around £10 billion to the UK Treasury every year.
What are the social facts regarding alcohols?
Around 20 per cent of all reports of violence take place in close proximity to a pub or club.
The estimated annual cost of alcohol-related crimes in the UK is approximately £8bn to £13bn.
What can ethanol be used for?
an extremely good solvent
the active ingredient in anti-bacterial hand cleansers, that do not require water
used as a fuel
What are biofuels?
Biofuels are produced from natural products, often plant biomass containing carbohydrate. As biofuels are produced from plants, they are renewable and theoretically carbon neutral.
What are the disadvantages of bioethanol?
The demand for biofuel crops means greater demand on rainforest land.
Crops grow slowly in parts of the world that have lower light levels and temperatures, so growing biofuel crops in these countries would not satisfy the demand for fuel.
For bioethanol to be burnt in a car engine, some engine modification is needed. Modern petrol engines can use petrol containing up to ten per cent ethanol without needing any modifications, and most petrol sold in the UK contains ethanol.
Although biofuels are in theory carbon neutral, this does not take into account the carbon dioxide emissions associated with growing, harvesting and transporting the crops, or producing the ethanol from them. Therefore, overall, more carbon dioxide is emitted than is absorbed, which means that it contributes to global warming.
Some people morally object to using food crops to produce fuels. For example, it could cause food shortages or increases in food prices.
How is vinegar produced?
When ethanol is oxidised by microbes, it forms a compound called ethanoic acid (CH3COOH), which is a form of carboxylic acid.
How is the presence of alcohol tested for?
alcohols are gently heated with a mixture of potassium dichromate(VI) and sulfuric acid, the mixture changes colour from orange to green
What is infrared spectroscopy?
When you shine infrared radiation through an organic chemical, certain wavelengths of the infrared radiation is absorbed.
The position of the peaks and troughs can tell you which chemical bonds are most likely to be present in the compound when you look at the wavenumber of each peak.
