Fuels and atmospheric science Flashcards
Where do they believe natural gas and crude oil to be from?
Formed from ancient remains of microscopic animals living in the sea. Then covered by layers of sediment and over millions of years they became natural gas and crude oil trapped in rocks
What is a finite resource?
A resource that limits our access to it as it is not made any more (or are being made very slowly)
What is crude oil made of?
A complex mixture of hydrocarbons
What are hydrocarbons?
Compounds that only contain hydrogen and carbon
How many covalent bonds can carbon atoms make?
4 bonds
What state is crude oil at at room temperature
Liquid
What is crude oil used for?
- fuels for vehicles, aircrafts, ships, heating and power stations
- feedstock or raw materials for the petrochemical industry
What are petrochemicals?
Substances made from crude oil such as polyethene
What is natural gas?
A mixture of hydrocarbons in the gas state
Give two fuels that can be obtained from crude oil and what they’re used for
- petrol - vehicles
- kerosene - aircrafts
What does non-renewable mean and give an example of a non-renewable source
It means a substance is being used up faster than they’re being made so one day they’ll run out - fossil fuels (e.g petrol)
How can crude oil be separated?
Fractional distillation
Where does the industrial fractional distillation take place?
In a large metal fractionating column
What is done to crude oil in the fractionating column
Heated strongly to evaporate it
Where is the column the hottest and coldest?
Hottest - bottom
Coldest - top
What happens to the vapours as they travel up the column?
They cool down and condense when the reach a part of the column that is cold enough (below their boiling points)
What happens to vapours with low boiling points
They don’t condense and leave the fractionating column as gases
What has the highest boiling point
Bitumen and it leaves the column as a hot liquid at the bottom
What is the order of substances produced in the column from top to bottom and give a use for all of them?
Gases - domestic heating and cooking
Petrol - fuel for cars
Kerosene - fuel for aircraft
Diesel oil - fuel for some cars and trains
Fuel oil - fuel for large ships and power stations
Bitumen - surfacing roads and roofs
Is each fraction pure hydrocarbons or a mixture?
Mixture of hydrocarbons
What is the trend in the number of atoms in molecules over the fractions?
Increases down the fractions
What is the trend for boiling point over the fractions?
Increases down the fractions
What is the trend of the ease of ignition over the fractions?
Easy at the top and difficult at the bottom
What is the trend for viscosity (how easy it is to flow) over the fractions?
Flows easily at the top and difficult at the bottom
What are alkanes?
Hydrocarbons that only have a single covalent bonds between the atoms in their molecules
What is a homologous series?
A sequence of compounds with the same functional group and similar chemical properties
What do the compounds in a homologous series have in common?
- molecular formulae of neighbouring compounds differ by CH2
- they have the same general formula
- they show gradual variation through physical properties (e.g melting point)
- they have similar chemical properties
Google what different hydrocarbons look like: including methane, ethane and propane
DID U DO IT???
U BETTER HAVE OR I WILL STEAL YOUR KNEECAPS
What are methane, ethane and propane?
The first three alkanes
How do methane, ethane and propane differ in their molecular formulas?
They each increase by one carbon atom and two hydrogen atoms
What is the general formula for the alkane homologous series?
C(n)H(2n+2)
meaning the number of hydrogen atoms is twice the amount of carbon plus 2
What is the trend between the number of carbon atoms and the boiling point?
As the number of carbon atoms increases, the boiling point gradually increases as well
Why can alkanes be separated through fractional distillation?
Because there is a difference in boiling points across them
What do alkanes produce when reacted with excess oxygen?
Carbon dioxide and water
What is combustion?
When hydrocarbon fuels react with oxygen in the air when they burn
What are two things that happen in complete combustion?
- only carbon dioxide and water are produced
- energy is given out
What needs to be present for complete combustion to take place?
A plentiful supply of air or oxygen (e.g bunsen burner with hole open)
What is the main hydrocarbon found in natural gas?
Methane
What is used to test the presence of water?
White anhydrous copper sulfate turning blue
What needs to be met in order for incomplete combustion to take place?
Limited oxygen/air
What happens during incomplete combustion?
- water is produced
- energy is given out (less than with complete)
- carbon monoxide and carbon are produced
What happens to the carbon atoms during incomplete combustion?
some are fully oxidised to become carbon dioxide, some are only partially oxidised to become carbon monoxide and some stay as carbon as smoke
Why is carbon monoxide dangerous?
It binds to the haemoglobin in the red blood cells and so prevents oxygen binding so causes unconsciousness and even death
Why can soot be dangerous
It can cause lung problems
What does carbon dioxide produce with water?
Acidic solutions
What is the pH of acid rain and what usually causes extra acidity?
Below 5.2 and its sulfur dioxide
Why do some hydrocarbons contain sulfur?
They occur as impurities and are attempted to be removed at oil refineries to reduce the environmental impact they produce
What happens to sulfur when hydrocarbon fuels are burnt?
It reacts with oxygen to produce sulfur dioxide
What happens to the sulfur dioxide in clouds?
It mixes with the water in the clouds and forms acids including sulfurous acid which is then oxidised and forms sulfuric acid
Why is it bad when the sulfuric and sulfurous acid falls as acid rain?
Crops do not grow well when the soil is too acidic and the excess acidity in rivers and lakes prevents fish eggs hatching and it kills insects and fish
What does acid rain do to buildings
‘Weathering’ where it breaks down the limestone or marble and also increases the rate of corrosion to metals such as iron (weakening them)
How do car engines work?
Fuel is mixed with air and ignited inside the engine, causing temperatures high enough for nitrogen and oxygen inside the engine to react together and this produces pollutants such as oxides of nitrogen
What does nitrogen dioxide produce when mixed with water
Dilute nitric acid
What is nitrogen dioxide
A toxic-red gas which causes bronchitis - catalytic converters in cars convert it into harmless gases
What does cracking do?
Breaks covalent bonds into hydrocarbon molecules
What do the vapours in the fractional distillation of crude oil pass?
A catalyst containing aluminium oxide heated to around 650 degrees - this speeds up reactions that are breaking down larger hydrocarbon molecules
What is the saturation of alkenes and alkanes?
Alkanes - saturated and a single bond between carbon
Alkenes - unsaturated and a double bond between carbon
What state is petrol at room temperature?
Liquid- making it easy to store
Why is petrol good for cars?
It is easily pumped to the engine and is easily ignited and so releases a lot of energy
What is the main difference between hydrogen fuel cells and petrol
Hydrogen fuel cells only produces water vapour, no carbon dioxide
What do hydrogen fuel cells do and not do?
They ignite easily and release a lot of energy like petrol, but they are gases at room temperature, making them hard to store as it needs to be pressurised
Why do scientists use other celestial bodies to investigate what Earth’s early atmosphere was like?
There is no life there yet and so it may be similar to Earth’s early atmosphere
What was the composition of the Earth’s early atmosphere
Mainly carbon dioxide with smaller amounts of water vapour and other gases and little or no oxygen
What is the reason for a lot of carbon dioxide in the early atmosphere?
Volcanic activity which released a lot of CO2
Why do some believe that the early atmosphere was also mainly nitrogen
Saturn’s moon titan is 98.4% nitrogen (probably also released from volcanoes) but Titan has an icy exterior so its unlikely that Earth’s atmosphere was like that
What formed the oceans?
The Earth cooled down causing water vapour to condense to liquid water which formed the oceans
How do scientists know there was not much oxygen in the atmosphere?
Oxygen pyrite is only formed when there is little or no oxygen as it is broken down by oxygen and is often found in ancient rock
How do scientists know about the oxygen increase?
Iron oxide started to form on the rocks, meaning that the oxygen levels increased and there is fossil evidence that microorganisms started to produce oxygen
What is the theory about oceans and the atmosphere
When the oceans were formed, the carbon dioxide dissolved in the oceans and reduced the amount of carbon dioxide in our atmosphere and sea creatures used the CO2 to make shells made of calcium carbonate
What is cyanobacteria?
Cyanobacteria grow in huge colonies and produce sticky mucus which traps layers of sand grains and other sediment. Organisms need to move over the sediment layers for sunlight access. Over time the sediment layers build up and form rocks called stromatolites
What do stromatolites have to do with the theories about the atmosphere?
They provide evidence that microorganisms were living at this time and caused an increase in oxygen
What did cyanobacteria evolve into?
Plants
How much of our atmosphere does oxygen make up?
21%
How is energy from the sun transferred to the Earth?
Through light and infrared
Explain the greenhouse effect
- Some energy is absorbed by the Earth, warming it
- Earth emits infrared waves
- Some gases in the air absorb this energy
- When the gases re-emit the energy, some of it goes back to the Earth’s surface and warms it
What are greenhouse gases and give some examples
Gases that absorb energy including carbon dioxide, methane and water vapour
What would happen without the greenhouse gases?
The Earth’s temperature would be a lot colder than it is today
What is causing what with global warming, the greenhouse effect and climate change
The increase in the greenhouse effect is causing global warming which is causing climate change
What is the main reason for the increase in carbon dioxide concentration in the atmosphere?
Industry and combustion
What is a casual link?
When one thing causes another
How can scientists see how much CO2 was in the early atmosphere?
By investigating the amounts of gas trapped in ice cores
Why aren’t old data readings very reliable
Thermometers back then were not very reliable and also aren’t fair as they are only taken from one place. Nowadays they’re taken from several places and are more accurate
What is a more powerful greenhouse gas than CO2 and when is it produced?
Methane as it absorbs energy better than CO2. It is produced when oil and natural gas are extracted from the ground and processed
Give two main sources of methane?
Livestock due to their digestive systems to digest tough grass
Paddy fields produce methane
Give the main effects of climate change
- increased flooding due to ice melting
- animal extinction if they cannot survive hotter temps
- drastic weather changes such as drought and heavy rainfall which affects crop growth
- CO2 is dissolved into oceans which harms the seas and coral may lose its colour due to the photosynthetic algae that they contain being pushed out
What can renewable energy sources do?
Reduce greenhouse gas emissions but it may not be enough
What are some global engineering suggestions to limit climate change
- reflect some of the sunlight back into space
- capture CO2 and bury it underground
- helping local people adapt to the new conditions such as building flood defences and dams but these may destroy habitats and there is a risk of them not working
