Crude oil Flashcards
what is the homologous series (1 mark)
a ‘family’ of organic compounds with the same functional group and similar chemical properties
what are hydrocarbons (1 mark)
compounds containing only hydrogen and carbon atoms
what is viscosity? (1 mark)
the thickness of a fluid
what is flamibility? (1 mark)
how easily a hydrocarbon combusts (burns)
What are the properties of hydrocarbons? (4 marks)
viscosity
- long chain hydrocarbons are extremely viscous
flammability
- short chain hydrocarbons are extremely flammable
boiling point
- short chain hydrocarbons have a low boiling point
Volatility
- short chain hydrocarbons have a higher volatility
general formula of alkanes
CnH2n+2
general formula of alkenes
CnH2n
What are the features of alkanes? (4 marks)
the form a homologous series
general formula
they are hydrocarbons
they are saturated
Explain how crude oil is formed (4 marks)
Crude oil is formed over millions of years from the remains of plankton, which were buried in the mud.
The mud stopped them from rotting away.
The oil from the dead animals got stuck under a layer of caprock, which will not let them through.
Why are alkanes ‘saturated’? (1 mark)
there are only single covalent bonds between carbon atoms
Explain the process of fractional distillation (4 marks)
Oil is heated to about 450°C and pumped into the bottom of a tall tower called a fractionating column, where it vaporizes.
The column is hotter at the bottom and cooler at the top. As the vaporized oil rises, it cools and condenses.
The heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column.
The lighter fractions (containing small molecules) have a low boiling point and condense near the top of the column
What is the order fractions are distilled in the fractionating column?
Liquid Petroleum Gas (LPG) - Short Chain Hydrocarbons
Petrol
Kerosene
Diesel Oil
Heavy Fuel Oil
Bitumen - Long chain hydrocarbons
What is a formulation? (1 mark)
A formulation is a mixture that is a useful product (e.g. toothpaste)
What is complete combustion? (2 marks)
This is when oxygen is unlimited, causing the reaction to produce carbon dioxide and water
What is the cause, problem and solution for the pollutant ‘carbon monoxide’?
CARBON MONOXIDE - formed due to incomplete combustion of fuels containing carbon atoms; can lead to carbon monoxide poisoning; can be reduced by providing sufficient oxygen during combustion
What is the cause, problem and solution for the pollutant ‘carbon dioxide’?
CARBON DIOXIDE - formed due to complete combustion of fuels containing carbon atoms; main greenhouse gas which contributes to climate change; emissions can be reduced by using renewable sources
What is the cause, problem and solution for the pollutant ‘nitrogen oxide’?
NITROGEN OXIDES - formed due to the oxidation of atmospheric nitrogen in the engine of a car, lorry etc; NOx gases can cause acid rain or react with other pollutants in the atmosphere to create photochemical smog; gas recirculation can reduce NOx emissions
What is the cause, problem and solution for the pollutant ‘particulates’?
PARTICULATES (e.g. soot) - formed due to incomplete combustion of fuels containing carbon atoms; can travel into the atmosphere, reflecting sunlight back into space and therefore cause global dimming; reduce vehicle emissions by switching to electric cars
What is the cause, problem and solution for the pollutant ‘water vapour’?
WATER VAPOUR - formed due to complete combustion of hydrocarbons; water vapour is an effective greenhouse gas and can radiate heat back into the Earth’s surface; can be reduced by reducing the levels of other greenhouse gases
What is the cause, problem and solution for the pollutant ‘sulfur dioxide’?
SULFUR DIOXIDE - formed during the combustion of fossil fuels containing sulfur impurities; can lead to acid rain; power plants can use scrubbers to remove sulfur dioxide from gases leaving the smokestack
What is cracking? (2 marks)
Thermal decomposition of long chain alkanes into shorter alkanes and alkenes
What are the types of cracking? (2 marks)
catalytic cracking
steam cracking
What is catalytic cracking?
Catalytic cracking
- Heat alkanes to vaporise them then pass over a hot (600–700°C) catalyst
What is steam cracking?
Steam cracking
- Heat alkanes to vaporize them and mix with steam and then heat to a very high temperature
Why are alkenes called unsaturated hydrocarbons? (2 marks)
they do not have the maximum number of hydrogens for every carbon atom; therefore they have a double bond
What is the test for alkenes?
add bromine water to a solution of alkenes
(will turn from orange to colourless)
Features of alkenes? (3 marks)
they are unsaturated hydrocarbons
they can be added together to form polymers
they are more reactive than alkanes (double bond)
Order of alkanes
Methane
ethane
propane
butane
pentane
Alkene + bromine —> ….
Alkene + bromine —> dibromo alkane
alkane + water (or steam) —> ….
alcohol
What is a monomer? (2 mark)
a small molecule that bonds with other small molecules to make a larger molecule (polymer)
What is a polymer? (2 mark)
a large, long chain made from many monomers joined together
what is an addition reaction? (2 marks)
when one molecule combines with another molecule to form a chain or a long molecule
What is volatility? (1 mark)
the tendency to turn into a gas
alkene + hydrogen —> ….
alkane
How to separate unreacted water with alcohol?
fractional distillation
heat the mixture in a round bottom flask
the alcohol will boil first
and evaporate up the fractionating column
and condense back into liquid
Explain the trend in the boiling points of alkanes.
The boiling point increases as the number of carbon atoms increase
This causes the intermolecular forces to increase
These intermolecular forces increase as the size of molecules increase
