Topic 8 Fuels And Earth Science (complete) Flashcards
Define what a hydrocarbon is
Compounds that contain only carbon and hydrogen
What is crude oil
Mixture of hydrocarbons with carbon atoms in chains
How is crude oil useful
Important source of useful substances as fuels
What does a finite resource mean
You will eventually run out of that resource
How is crude oil separated into its fractions by fractional distillation
(Size of molecules and boiling points)
Hydrocarbons with longer chains have higher boiling points so they turn back into liquids and drain out at the bottom
Hydrocarbons with smaller chains have lower boiling points so they get turned into gases and rise to the top and cool later
Give the uses for each
Gases
Petrol
Kerosene
Diesel Oil
Fuel Oil
Bitumen
Gases:domestic heating and cooking
Petrol:fuel for cars
Kerosene:fuel for aircraft
Diesel oil: some cars and trains
Fuel oil:large ships and power stations
Bitumen:road surfaces and roofs
How are the different fractions in hydrocarbons different
Number of carbon and hydrogen atoms in molecules
Boiling points
Ease of ignition
Viscosity
What is a homologous series
Compounds that have ;
Same general formula
Differ to each other by CH2
Gradual change in physical properties
Similar chemical properties
What is formula for complete combustion
Hyrdrocarbon + oxygen -> carbon dioxide + water
What do incomplete and complete combustion both produce(not a molecule)
Both give out energy
What is the difference between complete and incomplete combustion in terms of oxygen
Incomplete combustion takes place under limited supply of oxygen
What does viscosity mean
How easily a substance flows
High viscosity means thick
Why does incomplete combustion form carbon and carbon monoxide
Because there is less oxygen to make carbon dioxide
Why is carbon monoxide bad
Is a toxic gas as it binds with red blood cells to stop oxygen binding to them and can be fatal
What is soot
Black dust that reduces air quality ,makes surfaces dirty and cause respiratory problems
Sulfur dioxide comes from sulfur impurities in fossil fuels and what does it do
Dissolved in rain water to form sulfuric acid which causes acid rain
Why is acid rain bad
Lakes to be acidic plants and animals die
Damaged buildings trees and metals corrode
What are nitrogen oxides and how are they made
Reaction between nitrogen and oxygen when energy is released by combustion reactions and is a harmful pollutant
What are the advantages of using hydrogen gas to power vehicles
Hydrogen is a clean fuel
Only waste product is water
Renewable energy resource
What are the disadvantages of using hydrogen gas to power vehicles
You need a special expensive engine
Hydrogen gas still needs to be manufactured which still uses energy from burning fossil fuels
Hard to store
How are petrol kerosene and diesel oil obtained
Non renewable and obtained from crude oil
How is methane obtained
Non renewable fossil fuel found in natural gas
What is cracking
Breaking down of larger saturated hydrocarbon molecules (alkanes) into smaller more useful unsaturated ones (alkenes)
Why is cracking important
Longer chain hydrocarbons are usually less useful than the shorter hydrocarbon chains so cracking makes more of the shorter more useful ones
