Fuels Flashcards
Crude oil
A mixture containing hydrocarbons of different lengths
Another word for petroleum
What is fractional distillation?
The process of separating unhelpful crude oil into fractions: so hydrocarbons of the similar lengths for each use
Step 1 of fractional distillation
Vaporise crude oil at 350°c
However forms residue of longest chain hydrocarbons who’s boiling point is too high so remains as liquid
Step 2 of fractional distillation
Pass vapor and residue into fraction in column
Step 3 of fractional distillation
The residue will leave the fractioning column at the bottom
The gases will rise up. The column gets cooler at the top and so when the gases cool, they reach boiling point and condense to a liquid and leave
What property of hydrocarbons allow the hydrocarbons to be separated in fractional distillation?
They have different boiling points dependant on the carbon chain length = can be separated by condensing at different points in the fractioning column
Where do short chain hydrocarbons leave the column?
At the top at the coolest point = has lowest bp
Smallest do not condense but leave as gases, column isn’t cold enough to reach their bp
Where do long chain hydrocarbons leave the column?
At the bottom because they have the highest bp so condense near the bottom
Largest hydrocarbons drawn out liquified because they don’t vaporise at all
List of products formed from fractioning columns from the top (lowest bp) to bottom (highest bp)
Refinery gases
Petrol
Naphtha
Kerosene
Gas oil/ diesel
Mineral oil
Residue:
Fuel oil
Wax/grease
Bitumen
Refinery gases use
LPG, camping gas
Petrol use
Fuel cars
Naphtha use
Processed to make petrochemicals
Kerosene use
Jet fuel, central heating
Diesel use
Fuel cars
Mineral oil use
Lubricating oil
Fuel oil use
For ships and power stations
Was/grease use
Candles/ lubrication
Bitumen
Roofing/road surface
What process is done to convert heavier fractions to lighter, more useful fractions?
Cracking:
Catalytic
Thermal
How is crude oil and hydrocarbons used as fuel?
In combustion
What does complete combustion release?
Carbon dioxide and water
What does incomplete combustion release?
Unburnt carbon (soot)
carbon monoxide
Water
List of harm pollutants released when combusted for fuel
Carbon monoxide
Unburnt hydrocarbons
Oxides of nitrogen and sulfur
Carbon particulates
Carbon monoxide
A toxic gas because it binds to haemoglobin better than oxygen in our blood
So in high concentrations less oxygen is around our body = oxygen deprivation
Fatal possibly
What do both sulfur dioxide and oxides of nitrogen lead to?
Acid rain
Sulfur dioxide
When hydrocarbons containing sulfur are burnt, sulfur dioxide is released
Dissolves with moisture in the air and converted to sulfuric acid
Falls as acid rain
Oxides of nitrogen
Under high compression, nitrogen in air + oxygen from engine = oxides of nitrigen which dissolve in air’s moisture to form nitric acid then fall as acid rain
How do car exhausts stop pollutants from coming out?
With catalytic converter
Catalytic converters
Using platinum as a catalyst to change harmful pollutants to slightly less harmful pollutants like water vapour, nitrogen and co2
Alternatives to combusting fossil fuels for fuel
Making biofuels
Biofuel list
Biodiesel
Bio ethanol
Biogas
How is bioethanol made?
Fermentation of sugar maize crops
How is biodiesel made?
Refining fats and oils
How is biogas made?
Breakdown of organic waste matter
Why are biofuels a good alternative?
Because though they produce CO2 when burnt, CO2 is used up when growing plants (carbon neutral)
From waste which would go to landfill
Why are biofuels not a good alternative?
Not necessarily completely carbon neutral because CO2 is released in refining and transporting the fuel and other processes
Create problems in developing countries = food shortages of land used for this
Car engines need to be modified to work with them
