Crude Oil

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How is crude oil formed?
from the remains of dead plants and animals
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Is crude oil a mixture? What is a mixture?
Yes. A mixture contains two or more elements that are not chemically combined together
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What is a hydrocarbon?
A compound which contains carbon and hydrogen only
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Is crude oil useful on its own?
No, there are too many substances in it all with different boiling points. It is separated into useful products such as fuels
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What is crude oil?
a dark, smelly liquid that is a mixture of different hydrocarbons
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What is a fraction?
Hydrocarbons with similar boiling points separated from crude oil
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What kind of hydrocarbons are most useful?
Short chained hydrocarbons as the make good fuels because they ignite easily and burn well with few smoky flames
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What do short chained hydrocarbons have?
1)Lower boiling point 2)Low viscosity 3)Very flammable 4)Higher volatility
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What do long chained hydrocarbons have?
1)Higher boiling point 2)More viscosity 3)Less volatile 4)Less flammable (more smoky flames)
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What is fractional distillation?
A way to separate hydrocarbons from a mixture of hydrocarbons by boiling substances at different temperatures, then condensing and collecting the hydrocarbons
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How does fractional distillation work?
1)heated at the bottom of the fractionating column as hot vapor. 2)the column is hotter at the bottom and cooler at the top 3)gases condense when they reach their boiling points 4)Fractions collected as liquids at different levels continuously
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What do hydrocarbons with the smallest molecules have and where are they collected?
They have the lowest boiling points and are collected at the top of the column
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What do fractions at the bottom of the column have?
High boiling points and they cool to form thick liquids or solids at room temperature
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At what temperature is crude oil at the bottom and top of the column?
350ºC at the bottom and 50ºC at the top
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What is kerosene used as?
Aircraft fuel
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What is gasoline/petrol used as?
fuel in car engines
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What is residue?
very thick, sticky mixture of long chained hydrocarbons used in making roads and flat roofs
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What is diesel oil/gas oil used as?
fuel in diesel engines and as boiler fuel
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What is refinery/petroleum gas used as?
They are short chained hydrocarbons used as fuel
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When hydrocarbons burn in plenty of air, what do they release a lot of?
lots of energy
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What is the equation for complete combustion?
hydrocarbon + oxygen → carbon + water (always makes C0^2 and H^20)
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What is complete combustion?
When there is plenty of oxygen in the air, so elements in the fuel react fully with the oxygen
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When complete combustion takes place, what happens to the carbon and hydrogen atoms?
They are oxidised
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What is incomplete combustion?
Incomplete combustion occurs when the supply of air or oxygen is poor.
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What is the general equation for incomplete combustion?
hydrocarbon + oxygen → carbon monoxide + carbon (soot) + water
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What is carbon monoxide (CO)?
Carbon monoxide is a toxic gas that is colourless and odourless. When red blood cells pick up CO they carry it around your body instead of oxygen (lethal)
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Why must gas fires and boilers be serviced regularly?
To ensure there are no carbon monoxide leakages
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How are nitrogen oxides formed?
The high temperatures inside an engine allow nitrogen and oxygen in the air to react together. Nitrogen oxides irritate the lungs and cause acid rain
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What do catalytic converters do?
They convert carbon monoxide into carbon dioxide
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What is global dimming?
The reflection of sunlight back into space by tiny solid particles in the air. Can reduce photosynthesis.
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What is a particulate?
Small solid particle containing carbon and unburnt hydrocarbons given off from motor vehicles as a result of incomplete combustion. Thought to damage the cells in our lungs and even cause cancer
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Which type of engine burns hydrocarbons with bigger molecules?
Diesel engines burn hydrocarbons with bigger molecules than petrol engines
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Do all fossil fuels contain at least some sulfur?
Yes, and during combustion when it reacts with oxygen when burning a fuel, sulfur dioxide is formed
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Why is sulfur dioxide bad for the environment?
It is an acidic gas and when it dissolves in rainwater it causes acid rain
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Why is acid rain bad?
Damages trees and kills animal life in lakes, also corrodes limestone
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How can we prevent acid rain?
The sulphur impurities can be removed from fuel before it burns (diesel and petrol). We can also remove the sulfur dioxide released in 'flue' gasses from power stations by reacting it with calcium oxide or calcium hydroxide
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What is climate change?
The change in global weather patterns that could be due to excess levels of greenhouse gases in the atmosphere. Might result in severe weather events and the flooding of low-lying land and sea level rise
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What is carbon dioxide and why is it thought to contribute to climate change?
When any fuel containing carbon is burnt, carbon dioxide is produced and it is the main greenhouse gas in the air. It absorbs energy released as radiation from the surface of the earth
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What is smog?
mixture of smoke and fog
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What are biofuels and why will they become increasingly important?
Biofuels are fuels made from plant or animal products. They will become more important as our supplies of crude oil diminish
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What is biogas? What is biodiesel?
Biogas is gas generated from animal waste. Biodiesel which is made from oils extracted plants
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What are the advantages or biodiesel and other biofuels?
1)less harmful to animals and plants if spilled 2)burns more cleanly in an engine making little sulfur dioxide or particulates 3)carbon dioxide neutral 4)biofuels will become cheaper to use as the price of fossil fuels increases due to high demand
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What is meant by carbon dioxide neutral?
Crops used to make biofuels absorb carbon dioxide as they grow, which means that the amount of CO2 emitted when it burns is balanced by the amount absorbed when the plant grows.So, little contribution is made to the amount of CO2 in the atmosphere.
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Why can't we claim that biofuels make zero contribution to CO2 emissions? ?
Because CO2 is released when: -fertilising and harvesting crops -extracting and processing the biofuel -transporting the plant material and biofuel
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What are the disadvantages of biofuels?
1)Use of large areas of farmland to grow biofuels instead of food which could result in famine in poorer countries is food prices rise 2)Forests, which absorb lots of CO2 could be cleared to grow biofuel crop 3)Endangered habitats could be destroyed
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How is ethanol produced?
By fermenting sugar solution extracted from sugar beet or sugar cane using yeast. glucose → ethanol + carbon dioxide The ethanol is then distilled from the aqueous solution for use as biodiesel
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What is fermentation?
The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide
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Is ethanol carbon neutral?
In theory yes, because the sugar cane absorbs CO2 as it grows, and ethanol does give off carbon dioxide when it burns
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How is ethanol used as a fuel?
For use in cars and other vehicles it is usually mixed with petrol.
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Why would hydrogen be good as a fuel?
It burns with a very clean flame and the is no carbon in the fuel, so not carbon dioxide or pollutants released because water is the only product: hydrogen + oxygen → water. Also, water is a huge source of hydrogen (obtained by electrolysis)
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Why wouldn't hydrogen be a good fuel?
1) Electricity must be supplied for electrolysis (unless from a renewable source) 2)When mixed with air and ignited it is explosive (can't have leaks) 3)Gases take up much more room than liquids so storage is an issue-must use high-pressure cylinders
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What is a fuel cell?
The most efficient use of energy from oxidising hydrogen. The cells are fed with hydrogen and oxygen, which react to produce water and most of the energy in this reaction is transferred to electrical energy. Can be used to run a vehicle
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What is the problem with fuel cells in vehicles?
Need a constant supply of hydrogen
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Card 2


Is crude oil a mixture? What is a mixture?


Yes. A mixture contains two or more elements that are not chemically combined together

Card 3


What is a hydrocarbon?


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Card 4


Is crude oil useful on its own?


Preview of the front of card 4

Card 5


What is crude oil?


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