Topic 8 - Fuels and Earth Science Flashcards
What is crude oil a main source for?
Hydrocarbons
What forms crude oil?
Millions of years of high temperature and pressure on buried remains of plants and animals
What type of resource is crude oil?
Non-renewable (finite)
How is crude oil seperated?
It is heated until most of it has turned into gas and then enters a fractionating column
Describe the relation between hydrocarbon length and boiling point?
The longer the hydrocarbon, the higher the boiling point
Give the order of the hydrocarbons released from the fractionating column
Gases Petrol Kerosene Disel Fuel Bitumen
What is used for cooking and heating?
Gases
What are gases used for?
Cooking and heating
What is disel oil used in?
Fuel for cars and larger vehicles (eg Trains)
What is fuel oil used for?
Fuel for ships and power stations
What is bitumen used for?
Surfacing of roads and roofs
What three things must you be able to describe crude oil as?
A complex mixture of hydrocarbons containing molecules in which carbon atoms are in chains or rings
An important source of useful substances (fuels and
feedstock for the petrochemical industry)
A finite resource
Explain how crude oil is separated into fractions during fractional distillation?
Oil is heated until most of it turns into gas
Gases enter a fractionating column and the liquid part is drained off at the bottom
Since there’s a temperature gradient, the column is hot at the bottom and cooler at the top
The longer HC’s turn back into liquids and drain out lower down the column
Whilst, the shorter HC’s turn into liquids and drain out higher up the column
Explain how crude oil is separated into fractions during fractional distillation?
Oil is heated until most of it turns into gas
Gases enter a fractionating column and the liquid part is drained off at the bottom
Since there’s a temperature gradient, the column is hot at the bottom and cooler at the top
The longer HC’s turn back into liquids and drain out lower down the column
Whilst, the shorter HC’s turn into liquids and drain out higher up the column
What does the temperature gradient mean?
The column is hotter at the bottom and cooler at the top
What is a homologous series?
A family of molecules which have the same general formula and share similar chemical properties
Give examples of a homologous series of hydrocarbons
Alkenes
Alkanes
Give an example of a non-hydrocarbon homologous series
Alcohol
What is similar among compounds in a homologous series?
They have the same general formula
They differ by CH2 in molecular formulae from neighbouring
compounds
They show a gradual variation in physical properties (eg. Boiling point)
They have similar chemical properties
What determines which fraction a hydrocarbon will come out of?
It’s length (size)
What physical properties are there to do with hydrocarbons?
Ease of ignition
Boiling point
Viscosity
How does length of a hydrocarbon affect the boiling point?
The longer the HC, the higher the boiling point
Why does length of a hydrocarbon affect the boiling point?
The longer the HC, the stronger the intermolecular forces of attraction meaning the harder they are to break therefore a high temperature is needed
How does length of a hydrocarbon affect the ease of ignition?
The longer the HC, the harder to ignite
Why does length of a hydrocarbon affect the ease of ignition?
The shorter the HC, the more likely they are gases meaning they are easier to ignite than liquids
Why is it easier for a gas to ignite?
Because it will mix with oxygen in the air to produce a gas mixture which will burst into flames if in contact of a spark
How does length of a hydrocarbon affect the viscosity?
The longer the HC, the more viscous the liquid
Why does length of a hydrocarbon affect the viscosity?
The longer the HC, the stronger the intermolecular forces meaning harder it is for the liquid to flow
What is viscosity?
The measure of how easily a substance flows
What do fuels release in combustion reactions?
Energy
Why are hydrocarbons great fuels?
Their combustion reactions release alot of energy (very exothermic)
What is the complete combustion equation?
Hydrocarbon + Oxygen -> Carbon Dioxide + Water
Finish the balanced symbol equation to show the complete combustion of C9H20!
C9H20 + _O2 -> _H20 + _CO2
C9H20 + 14O2 -> 10H20 + 9CO2
What does complete combustion produce?
Carbon Dioxide and Water
What does incomplete combustion produce?
Carbon Dioxide, Carbon Monoxide, Water and Soot
Explain why the incomplete combustion of hydrocarbons can
produce carbon and carbon monoxide?
There is less oxygen therefore the products will have much less oxygen