Topic 8- Fuels and Earth Science Flashcards
(34 cards)
How is crude oil formed?
From the remains of plants and animals over millions of years
What is a hydrocarbon?
Compounds containing only hydrogen and carbon
How is crude oil separated?
The oil is vaporised
It then enters a fractionating column
In the column, there is a temperature gradient
The longer hydrocarbons have higher boiling points so they turn into liquids and drain out at the bottom
The shorter length hydrocarbons have lower boiling points so they turn to liquid and drain near the top
What is the order of the hydrocarbon fractions (smallest to largest)?
Natural gas
Petrol
Kerosene (paraffin)
Diesel oil
Fuel oil
Bitumen
What are the properties of a homologous series?
Same general formula
Similar chemical properties
Trends in physical properties
What happens to the hydrocarbons as the chain length increases?
Higher boiling point
Harder to ignite
Less viscous
What is incomplete combustion?
Where there isn’t enough oxygen for complete combustion, forming carbon monoxide
What happens if you breathe in carbon monoxide?
It stops oxygen from binding to red blood cells, leading to fainting/death
What happens when sulfur is combusted?
It forms sulfur dioxide which mixes with cloud causing acid rain. This damages stone buildings and can corrode metal
How is nitrogen oxide produced?
The energy released from combustion reactions cause nitrogen and oxygen to mix in the air, causing breathing difficulties
What are the uses for natural gas?
Heating
What are the uses for petrol?
Fuel for cars
What are the uses for kerosene?
Aircraft fuel
What are the uses of diesel oil?
Fuel for larger vehicles like trains
What are the uses of fuel oil?
Fuel for power stations and large ships
What are the uses of bitumen?
Surfacing roads
Why do we crack hydrocarbons?
There is more demand for shorter chains than longer chains
What are the conditions for cracking?
400- 700C
70atm
Aluminium oxide catalyst
What was phase 1 of the atmosphere?
Little or no oxygen
Volcanoes constantly erupted releasing carbon dioxide and water vapour
There was a small amount of steam, methane and ammonia
The water vapour later condensed to form the oceans
What was phase 2 of the atmosphere?
Lots of CO2 dissolved into oceans
Nitrogen was produced by ammonia reacting with oxygen and by denitrifying bacteria
Plants evolved, removing CO2 and producing O2 by photosynthesis
What was phase 3 of the atmosphere?
The build up of oxygen created the ozone layer which blocked harmful rays from the Sun and even more complex organisms to evolve
There’s virtually no CO2 left now
How does the greenhouse effect work?
The Earth re-radiates some of the radiation it absorbs as longer wavelength IR radiation
Some of this IR radiation is absorbed by greenhouse gases and some is re-emitted back towards the earth by greenhouse gases and some is re-emitted back towards space
Because the IR radiation is thermal radiation its absorption and re-emission by greenhouse gases helps keep the Earth warm
Why do big molecules have higher boiling points than small molecules?
Because the intermolecular forces of attraction break a lot more easily in small molecules than they do in bigger molecules because the forces are much stronger
Why are shorter hydrocarbons easier to ignite?
Because they have lower boiling points, so tend to be gases at room temp.
These gas molecules mix with oxygen in the air to produce a gas mixture which bursts into flames if it comes into contact with a spark
