Unit 10: Fuels & Earth and Atmospheric Science Flashcards
What are hydrocarbons? (2 mark)
Compounds that contain only hydrogen and carbon atoms
What is crude oil?
- Complex mixture of hydrocarbons
- An important source of useful substances
- A finite resource
What are some important fossil fuels obtained from crude oil?
- Petrol
- Kerosene
- Diesel Oil
- Bitumen
- Fuel Oil
Explain why crude oil is a finite resource (3 mark)
Crude oil takes a long time to be produced, and the rate at which humans are using it is too high for it to replenish, (demand is higher than the supply) so it is therefore non-renewable and not infinite
What state is crude oil in at room temperature?
Liquid
What does fractional distillation do to crude oil?
It separates crude oil into simpler, more useful mixtures that we use in our day to day life
Name the substances obtained from fractional distillation of crude oil
- Gases
- Kerosene
- Diesel Oil
- Fuel Oil
- Bitumen
What is the fraction of gases used for?
Domestic heating and cooking
What is the fraction of petrol used for?
Fuel for cars
What is the fraction of kerosene used for?
Fuel for aircrafts
What is the fraction of diesel oil used for?
Some cars, and trains
What is the fraction of fuel oil used for?
Fuel for large ships and in some power stations
What is the fraction of bitumen used for?
To surface roads and roofs
What does viscous mean?
Having a thick, sticky consistency between solid and liquid; having a high viscosity.
When something has a low viscosity, it flows easily
If I describe something as extremely volatile, what do I mean?
That it is easy to ignite
If I describe something as not very volatile, what do I mean?
That it is not easy to ignite
How does fractional distillation differ from distillation?
It differs from distillation only in that it separates a mixture into a number of different parts, called fractions
How does fractional distillation work?
- A tall column is fitted above the mixture, with several condensers coming off at different heights
- The column is hot at the bottom and cool at the top (it is heated from the bottom)
- Substances with high boiling points condense at the bottom, and substances with low boiling points condense at the top
- This works because different substances in the mixture have different boiling points
What are the properties of the gases at the top of the column?
- More Volatile
- Less Viscous
- Shortest Chain
- Lowest Boiling Point
- Easy to Ignite
What are the properties of the gases at the bottom of the column?
- More Viscous
- Less Volatile
- Longer Chain Length
- Higher Boiling Point
- Harder to ignite
What fraction has the lowest boiling point?
Gases
What fraction has the highest boiling point?
Bitumen
Which fraction has a boiling point between those of Gases and Kerosene?
Petrol
What fraction has a boiling point between those of Petrol and Diesel?
Kerosene
What fraction has a boiling point between those of Kerosene and Fuel Oil?
Diesel
What fraction has a boiling point between those of Diesel and Bitumen?
Fuel Oil
Explain how petrol and bitumen differ in their properties and uses? (6 Mark)
Properties:
- Petrol has a shorter chain length (or opp.)
- Petrol has lower boiling point (or opp.)
- Petrol has lower viscosity (or opp.)
- Petrol ignites/burns very quickly (or opp.)
- Bitumen does not combust completely due to high number of carbon atoms per molecule
- Burning Bitumen produces a lot of Carbon Monoxide & Soot
Uses:
Petrol: Fuel in cars/motorbikes/transportation
Bitumen: Used in surfacing roads/used for roofing/flooring
What is the molecular formula for Ethane?
C2H6
What is the molecular formula for Pentane?
C5H12
How are alkanes different to alkenes in their chemical formulas/compositions?
The relation between hydrogens and carbons in alkenes: H=2C
The relation between hydrogens and carbons in alkanes: H=2C+2
Name 2 general features of all homologous series.
- Their compounds all have similar chemical properties
- Their compounds all have the same general formula
What is the molecular formula for Ethene?
C2H4
What is the molecular formula for Pentene?
C5H10
What is the general equation for complete combustion?
Fuel + Oxygen —> Carbon Dioxide + Water
What is the balanced word equation for the complete combustion of Pentane?
Pentane + Oxygen —> Carbon Dioxide + Water
What is the balanced symbol equation for the combustion of methane?
CH4 + 2O2 —> CO2 + 2H2O
What is the balanced symbol equation for the combustion of propane?
C3H8 + 5O2 —> 3CO2 + 4H2O
When does incomplete combustion occur?
When there is a limited supply of oxygen
What happens during incomplete combustion?
- Water is produced
- Energy is given out (but less than the energy given out with complete combustion)
- Carbon Monoxide (CO) is released
- Carbon (C) is released in the form of soot
What are the problems with carbon monoxide?
Odourless, colourless gas which is toxic as it reduces amount of oxygen being carried around in blood.
How can the problems of carbon monoxide be reduced?
- Service all fuel burning appliances regularly
- Fit homes with carbon monoxide detectors
What are the problems with soot?
- Clogs pipes carrying waste gases away and can lead to fires
- Collects in lungs if sooty air inhaled leading to lung disease.
- Causes buildings to be dirty
How can the problems with soot be reduced?
Clean pipes regularly
What is the main/root cause of acid rain?
The burning of fossil fuels
What is a pollutant?
A substance released into the environment that can damage living things
What pollutants do engines produce?
Nitrous Oxides/Nitrogen Dioxide
Problems that acid rain can cause?
Reduces fish population, can make rivers and lakes too acidic, and can erode buildings and monuments
Which element from the soil can cause harm to aquatic organisms?
Aluminum
How are nitrous oxides made in engines?
High temperatures in engines force nitrogen and oxygen to react
How is acid rain created?
Burning fossil fuels releases sulphur dioxide, and high temperatures create nitrogen dioxide, which mix with water droplets and condense, forming clouds, and during precipitation fall to the ground in the form of acid rain
How can acid rain effect human life?
- Kill vegetation
- Cut off food sources
- Erode buildings and monuments
How can you tell when rain is acid rain?
Acid rain is more acidic than rain water, it has a Ph lower than 5.2
How is sulfur present in some hydrocarbon fuels?
Since it is present in crude oil as an impurity, it is part of hydrocarbon fuels that are made from crude oil
How does acid rain cause problems to plants on land?
It can dissolve into soil and be absorbed by plants, therefore killing the plants
What can acid rain do to some metals used for buildings?
It reacts with most metals, and corrodes them
What can acid rain due to rivers, lakes, and the life in them?
The water can get into rivers and lakes, making them acidic and killing off animals that cannot survive in that Ph level
What is the symbol equation for how nitrous oxides form?
What is the symbol equation for how sulfur oxides form?
N + O2 + heat = NO2
S + O2 + heat = SO2
Cracking Practical:
Why do the first few bubbles of gas need not be collected?
When the gas expands after being heated, it pushes the gas that is already in the tube out, which is air, so the first few bubbles are not the chemical product; they are the air that was in the tube.
Cracking Practical:
Why was broken pot included in the experiment?
It’s a catalyst, so it speeds up the chemical reaction.
Why do we use cracking?
Long-chain molecules are broken up because shorter chain hydrocarbon molecules have more demand than what is produced, so breaking the long chain hydrocarbons down makes shorter hydrocarbons, and helps meet the demand of the market. Smaller chain hydrocarbons like petrol have many more uses than long-chain hydrocarbons like bitumen, which is mainly used for road surfacing.
What does cracking a long-chain hydrocarbon produce?
A mixture of alkanes and alkenes
Fill in the blanks for the equation of cracking a long chain hydrocarbon:
C18H38 –> C5H10 + C13H(x)
Fill in the blanks for the equation of cracking a long chain hydrocarbon:
C15H32 –> 2C4H(x) + C7H16
Complete the equation for cracking:
C12H26 —> C2H6 + C6H12 + X
X = C4H8
Describe how life appeared on Earth:
- The early Earth’s atmosphere was mostly carbon dioxide (no oxygen) and water vapor that came from volcanic eruptions
- When the Earth cooled down, the water vapor condensed to form the oceans
- Carbon Dioxide dissolved in the oceans
- Life began in the oceans; the first life was unicellular organisms that could photosynthesize
- Photosynthesis caused carbon dioxide levels to decrease, and oxygen levels to increase
- When algae, plants etc. died, they sank to the bottom of the ocean and became buried in layers of sediment, and this sediment became compressed from sedimentary rock, oil and gas, which stopped it getting back into the atmosphere
- The atmosphere today is mostly Nitrogen (78%) and Oxygen (21%)
What planet’s atmosphere is similar to that of the Early Earth?
Mars
What are the two main greenhouse gases that cause climate change?
- Carbon Dioxide
- Methane
What activities release methane?
- Cattle Farming
- Growing Rice
- Landfills
What activities release carbon dioxide?
- Burning petrol in vehicles
- Deforestation
- Burning fossil fuels to generate electricity
What are some ways to mitigate climate change?
- Encouraging people to eat less meat
- Reducing the burning of fossil fuels by increasing nuclear energy
- Building flood defenses
- Building giant reflectors in space
- Burning methane as it is released
- Planting more trees
