4 Crude Oil And Fuels Flashcards
What are alkanes?2
- saturated hydrocarbons
- they contain many hydrogen atoms as possible in their molecules
Is crude oil useful straight out the ground?
No, because there are too many substances in it, all with different boiling points
What are hydrocarbons?
Compounds containing hydrogen and carbon
How can crude oil be separated using distillation?
Distillation separates liquids with different boiling points
What makes a fraction useful as a fuel?3
Lighter fractions make fuels as they ignite more easily and burn well, with cleaner flames
What does the boiling point of hydrocarbons depend on?
The size of its molecules
What is in crude oil?
Crude oil is a mixture of many different compounds
How do the number of carbon atoms vary between hydrocarbons?
They don’t there are similar number of carbon atoms
Why do different fractions boil at different temperatures?
Their molecules are different sizes
What are the products of combustion when we burn fuels in a good supply of air?2
The carbon and hydrogen in the fuel are completely oxidised
They produce carbon dioxide and water
What does changing the conditions which hydrocarbon fuels are burnt do?
Changes the products made
What are the products of combustion when we burn fuels with a lack of air?2
Poisonous carbon monoxide gas is formed
We also get particulates of carbon and unburnt hydrocarbons especially if the fuel is diesel
When we burn fossil fuels what does the sulfur inside of them form?3
A poisonous gas sulfur dioxide
It is acidic
It is bad for the environment and is the cause of acid rain
What does a caralytic converter do?
It reduces the carbon monoxide and nitrogen oxides produced by a car engine
Name harmful substances that may be produced when fuels burn?3
Sulfur dioxide, nitrogen oxide, carbon monoxide
What are biofuels?
Renewable source of energy that could be used to replace fossil fuels
What can biofuels be made from?
Vegetable oils
Advantages of biodiesel?5
- less harmful to animals and plants than crude oil if spiller
- burns more cleanly
- makes very little sulfur dioxide
- it will become cheaper as supplies of other things run out
- produces useful products
Disadvantages of biodiesel?3
- large areas of farmland are needed to produce fuel instead of food
- could destroy habitats
- a perfect temperature needed for use
Why are alkanes described as saturated hydrocarbons?
Because they contain as many hydrogen atoms as possible in each molecule and no more hydrogen atoms can be added
What are the advantages of using fermentation to make ethanol?
It uses renewable plant material
What are the disadvantages of using ethene to make ethanol?
It needs non-renewable crude oil as its raw material
How does fractional distillation work?
The fractionating column works continuously
Heated crude oil piped in at the bottom
The vaporised oil rises up the column
The various fractions are constantly tapped off at the different levels where they condense
For alkanes the shorter the molecules… The ?
Less viscous (gloopy) More volatile - lower boiling point More flammable
Explain the process of fractional distillation?
Crude oil is heated to 350
Most of the compounds in the crude oil evaporate
Any liquids flow down to the bottom of the column and the hot vapours rise up
When the hot vapours rise up the column the vapours cool
When a fraction in the vapours cools to its boiling point, the fraction condenses
Why is carbon monoxide produced?
When incomplete combustion occurs of a fuel
What is produced when anything burns completely?
Carbon dioxide
Water
Where is the crude oil column hottest?
At the top
What does unsaturated mean?
Contains a carbon carbon double bond
What happens when iodine is added to oil?
Iodine is decolourise D
Why does crude oil need to be fractionally distilled?
Is a mixture of hydrocarbons
Long chain hydrocarbons tend to have?
High boiling point
Low volatility
High viscosity
Low flammability
Properties of short chain hydrocarbons?
Low boiling point
High voltality
Low viscosity
High flammability
