Organic chemistry Flashcards
(27 cards)
Crude oil
is a finite resource that is found in the Earth’s crust. It is the remains of organisms that lived and died millions of years ago
Crude oil is an important source of:
Fuels: such as petrol
Feedstock for the petrochemical industry
Alkanes properties
differ by CH2 in molecular formulae from neighboring compounds
Methane molecular formula
structural formula
ball and stick model
https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/large
Ethane
molecular formula
structural formula
ball and stick model
https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/large
Propane
molecular formula
structural formula
ball and stick model
https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/large
Butan
molecular formula
structural formula
ball and stick model
https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/large
Why are alkanes saturated hydrocarbons
they are hydrocarbons because they only contain hydrogen and carbon and saturated because their carbon atoms are joined by C-C single bonds
How does fractional distillation work
heated crude oil enters a tall fractionating column,
which is hot at the bottom and gets cooler towards the top
vapours from the oil rise through the column
vapours condense when they become cool enough
liquids are led out of the column at different heights
Why is fractional distillation used
Fractional distillation is used to separate crude oil into simpler, more useful mixtures. This method can be used because different hydrocarbons have different boiling points.
Why do smaller hydrocarbons have low BP
They have weak IMF so they do not condense, but leave the column as gases. long hydrocarbons molecules have stronger IMF’s, so they have high boiling points. They leave the column as hot liquid bitumen
The fractions of distillation what are they use this fun thingy
Lazy Penguins Keep Drinking Hot Beer.
Lazy = liquefied petroleum gases
Penguins = petrol
Keep = kerosene
Drinking = diesel
Hot = heavy fuel oil
Beer = bitumen
Small molecules properties fractional distillation
low BP
very volatile
flows easily
ignites esaily
Large molecules properties fractional distillation
High BP
not very volatile
does not flow easily
does not ignite easily
Complete combustion of a hydrocarbon fuel occurs when
there is a good supply of air. Carbon and hydrogen atoms
in the fuel react with oxygen in an exothermic reaction:
What occurs after a complete combustion of a hydrocarbon
carbon dioxide and water are produced
the maximum amount of energy is given out
Write a balanced equation for the complete combustion of methane, CH4, found in natural gas.
CH4 + 2O2 → CO2 + 2H2O
Incomplete combustion occurs when
The supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced. Less energy is released than during complete combustion.
Cracking
Cracking is a reaction in which larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules, some of which are unsaturated:
C16H34 is an alkane which can be used as the starting chemical in cracking. One of the products of cracking this compound is an alkane which has 10 carbon atoms in it. Write a balanced symbol equation for this cracking reaction.
C16H34 → C10H22 + C6H12
Catalytic cracking
Catalytic cracking uses a temperature of approximately 550°C and a catalyst known as a zeolite which contains aluminium oxide and silicon oxide
Steam cracking
Steam cracking uses a higher temperature of over 800°C and no catalyst
Two important reasons for cracking
It helps to match the supply of fractions with the demand for them.
It produces alkenes, which are useful as feedstock for the petrochemical industry.
explain the current supply and demand situation of crude oil
The supply is how much of a fraction an oil refinery produces. The demand is how much of a fraction customers want to buy. Very often, fractional distillation of crude oil produces more of the larger hydrocarbons than can be sold, and less of the smaller hydrocarbons than customers want.
