2.5 Crude Oil, Fuels and Organic Chemistry

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?

● The crude mixture is put into the fractionating column at the bottom and is 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 at all, is called bitumen.

What are fractions in fractional distillation?

Fractions contain mixtures of hydrocarbons (alkanes) with similar boiling points.

What are the trends in properties of fractions with increasing chain lengths?

● Boiling and melting point increases
● Viscosity increases
● Flammability increases
● Volatility increases
● Their colour darkens
● Their usefulness as fuels decreases

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 hard for poorer countries to buy oil.

● Wars or internal crisis within a country that produces oil can affect 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 is the social impact of the oil industry?

The oil industry supplies jobs and money to the economy.

What are the environmental impacts of the oil industry?

● Burning 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 habitats.

● Oil spillages into the ocean result in the deaths of marine life and birds and are often dealt with by setting them alight.

What are the combustion reactions of hydrocarbons?

● When hydrocarbons burn in plenty of oxygen it will combust as follows:
hydrocarbon + oxygen -\> carbon dioxide + water

● When hydrocarbons burn with insufficient oxygen it will combust as follows:
hydrocarbon + oxygen -\> carbon monoxide + water

What is calorimetry?

An experimental technique used to work out the energy released when burning a fuel.

What is the method of calorimetry?

● A known volume of water is added to a calorimeter and the temperature is recorded.

● A known mass of fuel is burnt beneath the calorimeter.

● The maximum temperature of the water and the final mass of the fuel is recorded.

● Energy released (Joules)\= mass of water (g) x temp change x 4.2.

● Energy per gram of fuel \= energy released (J) / mass of fuel burned (g).

What is the combustion reaction of hydrogen and what are its uses?

● Hydrogen burns in oxygen and forms water.
● Hydrogen is used as 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 - must be cooled to very low temperatures so it liquifies for storage and transport.

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, so knowledge of the fire triangle can be used to prevent and put out fires.

What is hydrocarbon cracking?

Breaking long chain hydrocarbons down into shorter and more useful chains.

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 where n is the number of carbon atoms in the molecule.

What is the general formula of alkenes?

CnH2n where n is the number of carbon atoms in the molecule.

What are some examples of simple alkanes? List down their names and molecular formulas.

1. Methane, CH4
2. Ethane, C2H6
3. Propane, C3H8
4. Butane, C4H10

What are some examples of simple alkenes? List down their names and molecular formulas.

1. Ethene, C2H4
2. Propene, C3H6
3. Butene, C4H8

What is isomerism?

When two compounds have the same molecular formula (same number and type of each atom) but their structures differ in some way).

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.

What are addition reactions?

Reactions in which two or more molecules combine to form a larger one with no other products.

What is the test for alkenes?

Bromine water is an orange solution. When shaken with an alkene, the bromine water will decolourise as the bromine reacts with the alkene to form substituted alkanes. This is an addition reaction

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.

What are the uses of polyethene?

● Bin liners
● Hoses and tubes
● Plastic bags
● Plastic bottles

What are the uses of polypropene?

● Plastic for cars
● Packaging
● Textiles

What are the uses of polyvinyl chloride (PVC)?

● Water pipes
● Window panes
● Medical tubing and IV bags
● Electrical wires

What are the uses of poly(tetrafluoroethene) (PTFE)?

● Coating non-stick pans
● Coating hair straighteners and curlers
● Nail polishes

What are the general properties of polymers?

● Thermo-softening polymers melt when heated and can be remoulded and reshaped.

● Thermosetting polymers do not melt when heated.

● High-density polymers tend to be harder and stronger than low-density polymers.

What are the environmental issues relating to the disposal of plastics?

● Plastics are non-biodegradable.
● Increasing pressure on landfill sites for waste disposal.

What are the methods for disposing plastics?

● Landfill sites.
● Incineration disposal - however this releases carbon dioxide, a greenhouse gas.
● Recycling - this manages the other issues of disposal, provides jobs and helps preserve the non-renewable source of crude oil.

How is ethanol produced?

The fermentation of sugar using yeast - the enzymes in yeast catalyse the reaction.

Glucose -\> Ethanol + Carbon dioxide

What conditions are required for yeast enzymes to work?

* Temperature of the range 20-40
* Absence of oxygen
* A pH of the range 4 to 7

How is ethanol obtained from the mixture during fermentation?

Yeast is removed by **filtering**.

Then the ethanol and water (and some sugar) mixture is distilled.

What is the test for alcohol?

● Add a few drops of acidified potassium dichromate solution to the sample.

● Gently heat.

● If alcohol is present, the solution will change from orange to green.

What are the uses of ethanol?

● Found in alcoholic drinks.
● Used as a solvent- it dissolves a large number of substances easily.
● Used 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.

● Costs 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 carbon dioxide 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 the burning of fossil fuels so it will still cause global warming.

● Engines must be altered before they can use bioethanol as a fuel.

● Can cause deforestation to provide land for growing sugar cane.

● Some areas of the world are not hot enough and don't have enough light hours in the day to be able to completely switch to biofuel.

● Using food as fuel can increase food prices.

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 the suffix becomes -diol,-triol, -tetrol.

What are potential isomers of alcohols?

● Isomers are compounds which have the same molecular formula but different structural formula.

● This means that isomers of alcohols have the same molecular formula but the -OH alcohol group is positioned at a different carbon atom thus giving the compound a different structural formula.

What is the oxidation of ethanol?

● When acidified potassium dichromate is added to ethanol, it is oxidised it forms ethanoic acid, a carboxylic acid which has the functional group -COOH.

● The solution changes colour from orange to green.

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 absorb 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.