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