2.5 Crude Oil, Fuels and Organic Chemistry Flashcards
What are hydrocarbons
Compounds containing ONLY carbon and hydrogen atoms
What is a hydrocarbon chain
Carbon atoms forming bonds with other carbon atoms
Longer the hydrocarbon chain- higher or lower the boiling point
Higher
What is crude oil
A complex mixture of hydrocarbons formed over millions of years from the remains of simple marine organisms
How can crude oil be separated
Fractional distillation
Temperature of the fractionating column
It has a temperature gradient- high at bottom low at top
What happens to crude oil before it enters the fractionating column
It is boiled/vaporised
The lower the boiling point the——in the column the compound is collected
Higher
What are fractions
Mixtures containing hydrocarbon compounds with similar chain lengths therefore similar boiling points
Why do larger hydrocarbon chains have higher boiling points
Molecules are held together by intermolecular forces- larger molecules, more intermolecular forces; more energy needed to overcome them in order to melt/boil
Longer chain molecules are more or less viscous
More viscous- harder to pour
Where in the fractionating column are small molecules found
Top
Where in the fractionating column are large molecules found
Bottom- high b p
What does burning hydrocarbons require and produce
Requires O2 from the air
Produces carbon dioxide and water
Equation for burning methane in air
CH4➕2O2➡️CO2➕2H20
Why are the shorter chain hydrocarbons better fuels
Easier to vaporise
Economic and political issues of the oil industry
Price of oil =set by oil producing countries(poor countries who need oil have to pay going rate- not in control of their economy)
War affects oil supply, this could affect economy
Political disagreement countries can cut off others oil supply
Social and environmental issues of the oil industry
Burning fossil fuels- increase global warming
Oil spills- cause major pollution incidents
Power Plant- eye sore /spoils countryside and habitats
Ethanol isn’t a hydrocarbon but
What does burning ethanol in air produce
Same products as burning hydrocarbons
CO2 and water
Burning ethanol- what happens if supply of oxygen is limited
Incomplete combustion
Forming carbon (soot) and carbon monoxide (poisonous) in addition to usual products(water and co2)
What does the combustion of fuel containing impurities (e.g compounds of sulfur) form
Sulfur dioxide causing acid rain
What does burning hydrogen produce
Equation
Only water
2H2➕O2➡️2H2O
advantages of hydrogen as a fuel
Renewable
No CO2 emissions when burned
Disadvantages of using hydrogen as a fuel
Made by reacting steam with coal/gas or passing electricity through water (electrolysis)- not carbon neutral - CO2 produced
Very flammable- dangerous
Catalytic cracking definition
Large hydrocarbons can be broken into smaller ones
How does catalytic cracking work
What is also formed
Heating heavier fractions to a high temp in the presence of a catalyst
An alkene is also formed
Why is catalytic cracking done
There is a greater demand for smaller hydrocarbons
Alkenes are used to make plastics
Properties of plastics
Good thermal and electrical insulator
Flexible strong low density don’t rot/corrode
Formula for the chemical symbol of an ALKANE
CnH2n+2
Formula for the chemical symbol of an ALKENE
CnH2n
Alkane structure
n carbons bonded together by single bonds, H atoms wherever else possible single bonds
What are alkenes
Unsaturated hydrocarbons which have a double bond between 2 carbon atoms