Section 16 - Fuels Flashcards
Why are natural gases and crude oil made from?
They’re natural resources formed from ancient remains of microscopic animals and plants that once lived in the sea
How did dead animals and plants develop to become natural gas and crude oil?
The remains became covered in layers of sediment, over millions of years and naturally turned to natural gas and crude oil
Why is natural gas and crude finite resources?
Because they aren’t made anymore (are made extremely slowly) so they’re limited to us
What does finite mean?
Will run out
What is crude oil made up of?
A complex mixture of hydrocarbons
What is a hydrocarbon?
A compound that contains hydrogen and carbon atoms only
How many covalent bonds can each carbon atom hold?
4
In what shapes can you find hydrocarbons?
Lines or rings
What are the first 4 hydrocarbons?
Methane, ethane, propane, butane
What is the mnemonic to remember methane, ethane, propane and butane?
Monkeys Eat Peanut Butter
What is the symbol name for Methane, ethane, propane and butane?
CH4 , C2H6 , C3H8 , C4H10
What varies a hydrocarbons physical state?
Its size and complexity
What state is crude oil at room temperature?
Liquid
What substances is crude oil useful for?
Fuels for: vehicles, aircrafts, ships, heating and power stations / feedstock or raw materials for petrochemical company
What is a petrochemical?
A substance made from crude oil, such as poly(ethene) and other polymers
What is natural gas?
It’s a mixture of hydrocarbons in the gas state
What is the main hydrocarbon for natural gas and what is it useful for?
Methane / useful for cooking
Which liquid fuels can be obtained from crude oil?
Petrol, diesel oil, kerosene
What does non-renewable mean?
They are being used faster than they’re being formed - if we keep using them, they’ll run out one day
How can you separate hydrocarbons to be simpler, as more useful mixtures?
Fractional distillation
Why does fractional distillation elf to separate hydrocarbons?
Because different hydrocarbons have different boiling points
When does fractional distillation take place?
In a fractioning column
Why is crude oil heated strongly in the fractionating column?
To evaporate it
State the process that happens to crude oil in a fractionating column
Column is hottest at the bottom & coldest at the top / vapours rise through columns to cool down / vapours condense when they reach a part of the column that is cool enough / liquid falls into tray and is piped away / lowest boiling point doesn’t condense at all
What hydrocarbon has the highest boiling point and leaves the bottom as a hot liquid?
Bitumen
What are the separate liquids and gases called?
Oil fractions / because they’re only parts of original crude oil
Name the 6 fractions in a fractionating column in order of highest boiling point to lowest
Bitumen / fuel oil / diesel oil / kerosene / petrol / gases
What is bitumen used for?
Surfacing roads
What is fuel oils main purpose?
For large ships and power stations
What is diesel oil most useful for?
Cars and trains
What is kerosene most useful for?
Fuel for aircrafts
What is petrol most useful for?
Fuel for cars
What is gases most useful for?
Domestic heating and cooking
Is a fraction a pure hydrocarbon or a mix?
A mixture of hydrocarbons
How come hydrocarbons, even though mixed, still come out as one?
They have similar numbers of carbon and hydrogen atoms in their molecules, and similar boiling points
Why do different fractions have different uses?
Because they have different properties
Which fraction has the lowest and highest number of atoms in molecules?
Smallest - gases (1-4 carbon atoms) largest - bitumen (>kn atoms)
Which fraction has the lowest and highest boiling point?
Gases - lowest <0 / bitumen - highest >350
Which fraction has the easiest / most difficult ease of ignition?
Easies pr to ignite - gases / difficult to ignite - bitumen
Which fraction has the lowest / highest viscosity?
Gases - flows most easily / bitumen - flows with difficulty
What compounds are their mostly in crude oil?
Alkanes
What are alkanes?
Hydrocarbons that only have single covalent bonds between the atoms in their molecules
What is a homologous series?
When alkanes form a family of compounds
What are hydrocarbons like methane and ethane?
They are alkanes
What general formula do alkanes use?
CnH2n+2
What does the alkane general formula mean?
The we know the number of carbon atoms in the alkane then we can calculate the number of hydrogen atoms
How do we calculate the number of hydrogen atoms?
Carbon atoms x 2 and then +2
Why type of molecules are alkanes?
They are saturated molecules
Why are alkanes saturated molecules?
Because the carbon atoms are fully bonded to hydrogen atoms
What does a carbohydrates contain?
Carbon, hydrogen and oxygen
But type of bonds could you get between carbon?
Single, double or triple
As the number of carbon atoms increase, what happens to the boiling points of alkanes?
The boiling point increases
What does the boiling point of a straight-chain alkane depend upon?
The size of its molecules
Alkanes react with oxygen and produce what?
Carbon dioxide and water
What is the equation for propane found in camping gas?
Propane + oxygen = carbon dioxide + water
Why do hydrocarbon fuels react with when they burn in the air?
Oxygen
