Unit 2.5 - Crude Oil, Fuels and Organic Chemistry Flashcards
What are hydrocarbons?
Molecules made up of only carbon and hydrogen.
What is crude oil?
Crude oil is a complex mixture of hydrocarbons formed over millions of years from the remains of simple marine organisms.
What molecules does crude oil contain?
Crude oil contains dozens of hydrocarbons with carbon chains of varying lengths.
What happens in a fractioning column?
Crude oil is vaporised/boiled before entering the fractioning column, and the hydrocarbons present in the mixture condense at different temperatures (and hence various heights in the column (the lower the boiling point, the higher up the column the fraction is collected).
What is a fraction?
A mixture containing hydrocarbons (alkanes) that have similar boiling points and chain lengths.
Name and uses of fraction with lowest boiling point
Petroleum gases - fuel for domestic heating and cooking.
Name and uses of fraction with second-lowest boiling point
Petrol/Gasoline - Fuel for cars
Name and uses of fraction with third-lowest boiling point
Naptha - Used to make chemicals
Name and uses of fraction with fourth-lowest boiling point
Kerosene - Fuel for aircraft
Name and uses of fraction with fifth-lowest boiling point
Diesel - Fuel for some cars and trains
Name and uses of fraction with sixth-lowest boiling point
Lubricating oil - Used to reduce friction in machinery
Name and uses of fraction with seventh-lowest boiling point
Fuel oil - Fuel for ships and power stations
Name and uses of fraction with highest boiling point
Bitumen - Used for roads and roofs
What 4 trends in properties are there as you go up the fractioning column?
Chain length (decreasing), Boiling point (decreasing), Volatility/Ease of evaporation (increasing) and Flammability (increasing).
What other property changes between fractions in the column?
Colour - Bottom fraction is black, middle fractions range from brown-yellow and top fraction is colourless.
Describe the social, political and economic importance and impacts of the oil industry. (2)
- Rapidly growing economies (India, China) will use more energy every year and supplying that energy using crude oil is not sustainable in the long term.
- Growing demand or wars in oil producing countries drives prices upwards, affecting individuals’ heating and transport costs, and indirectly causing inflation (e.g. in food prices).
Describe the environmental impacts of the oil industry (2).
- Burning fossil fuels releases carbon dioxide into the atmosphere, which contributes to global warming, and releases sulfur dioxide, which causes acid rain.
- Oil spillages can kill thousands of fish and sea birds, and are expensive and difficult to clean up.
What difficult decision/choice may have to be made in the future regarding the use of crude oil?
Many important products, such as plastics and medicines, are made using components of crude oil, and so people will eventually have to decide whether to burn the remaining reserves of crude oil or use it for other purposes.
What is required and produced in the combustion of hydrocarbons?
The combustion of hydrocarbons requires oxygen (from the air) and produces carbon dioxide and water; it is exothermic and releases useful energy (mostly thermal, but some light energy).
Briefly describe an experiment to compare the energy released per gram of different fuels.
- Measure and record the mass of a spirit burner containing a known alcohol (e.g. methanol, ethanol).
- Place the spirit burner 2-3cm below a conical flask containing 100cm^3 of water, held in place by a clamp stand.
- Place a thermometer into the conical flask and measure the starting temperature.
- Light the spirit burner and allow it to burn until the water temperature has risen by approximately 40C.
- Record the end temperature of the water and the end mass of the spirit burner and its contents.
- Repeat steps 1-5 with several other fuels.
What is formed in the combustion reaction of hydrogen?
Only water is produced (no carbon dioxide).
What are the two main uses of hydrogen as a fuel?
In rocket fuel and in hydrogen fuel cells that are now being used to power cars.
Explain the term combustion.
A fuel reacting with oxygen to release useful energy (the reaction is exothermic). Most of the energy released is thermal, some is light energy. When a fuel burns in plenty of air, there is enough oxygen for complete combustion.
Explain the advantages of using hydrogen as a fuel.
- Hydrogen is produced from water so it is renewable.
- Water is the only product of the combustion of hydrogen, so does not contribute to global warming or acid rain.
Explain the disadvantages of using hydrogen as a fuel.
- It requires large amounts of electricity to produce hydrogen from water via electrolysis (this electricity is expensive to generate).
- Storage of hydrogen requires bulky and heavy pressurised containers and is potentially hazardous as it forms an explosive mixture with air.
