C9 Crude oil and fuels Flashcards
Alkane
Saturated hydrocarbon with the general formula CnH2n +2, for example methane, ethane and propane. Each carbon atom forms four single covalent bonds.
Alkene
Unsaturated hydrocarbon with a carbon-carbon double bond, its general formula is CnH2n
Cracking
The reaction used in the oil industry to break down large hydrocarbons into smaller, more useful ones
Distillation
Separation of a liquid from a mixture by evaporation followed by condensation
Double bond
A covalent bond made by the sharing of two pairs of electrons
Flammable
Easily ignited and capable of burning rapidly
Fraction
Hydrocarbons with similar boiling points separated from crude oil
Fractional distillation
A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids
Hydrocarbon
A compound with only hydrogen and carbon
Mixture
When some elements/compounds are mixed together, but do not react together. Mixtures are not pure substances.
Oxidised
A substance that has oxygen added to it/it has lost electrons
Saturated hydrocarbon
A hydrocarbon with only single bonds between its carbon atoms, contains as many hydrogen atoms as possible in each molecule
Thermal decomposition
The breakdown of a compound by heating it
Unsaturated hydrocarbon
A hydrocarbon whose molecules contain at least one carbon - carbon double bond
Viscosity
A liquid’s thickness/resistance to flowing or pouring
Homologous series
A group of organic compounds that react in a similar way e.g. alkanes and alkenes
First four alkanes
Methane: CH4
Ethane: C2H6
Propane:C3H8
Butane: C4H10
How does the length of the carbon chain affect the properties of a hydrocarbon?
The shorter the carbon chain, the more runny and less viscous a hydrocarbon is.
The shorter the carbon chain, the more volatile hydrocarbons are(they have lower boiling points).
The shorter the carbon chain, the more flammable(easier to ignite) the hydrocarbon is.
Equation for the complete combustion of a hydrocarbon
Hydrocarbon + oxygen: carbon dioxide + water vapour + energy
Waste products in complete combustion of a hydrocarbon
Carbon dioxide and water
How was crude oil formed
Crude oil is a fossil fuel formed from the remains of plants/animals like plankton that died millions of years ago and were buried in mud. Over millions of years, with high temperature and pressure, the remains turned to crude oil, which are drilled up from the rocks it’s found
Finite resources
Non-renewable Resources that will run out as they aren’t formed quickly enough to be considered replaceable, fossil fuels like coal, oil and gas
Crude oil
A mixture of lots of different hydrocarbons, most of which are alkanes
Stages of fractional distillation
1) Oil is heated until it turns into gas. The gases enter a fractionating column(and the liquid bit is drained off).
2) In the column there’s a negativemtemperature gradient(it’s hotter at the bottom and gets cooler as you go up).
3) The longer hydrocarbons have high boiling points. They condense into liquids and drain out of the column early on, when they’re near the bottom. The shorter hydrocarbons have lower boiling points, so condense and drain out later on, near the top of the column where it’s cooler.
4) You end up with the crude oil mixture being separated into different fractions, each fraction has a mixture of hydrocarbons with a similar number of carbon atoms, so have similar boiling points. These fractions have different boiling points so condense at different places in the tower
Organic compounds
Compounds containing carbon atoms
Short-chain hydrocarbon uses
Are flammable so are useful fuels e.g. petrol for cars and paraffin for jet fuel and are in high demand as well was kerosene
Uses of crude oil
Oil provides fuel for modern transport
The petrochemical industry uses hydrocarbons as feedstock to make new compounds for use in things like polymers, solvents, lubricants and detergents
Used as fuels e.g. petrol for cars, paraffin for jet fuel,
Cracking
How longer alkane molecules produced by fractional distillation are turned into smaller, more useful ones. It’s a thermal decomposition reaction as it involves breaking molecules down by heating them.
Uses of alkenes
Alkenes are more reactive than alkanes. They’re used as a starting material when making other compounds and can be used to make polymers.
How does bromine water test for alkenes
1) When orange bromine water is added to an alkane, no reaction will happen and it’ll stay bright orange,
2) If it’s added to an alkene the bromine reacts with the alkene to make a colourless compound, so the bromine water is decolourised
Long-chain hydrocarbon uses
Heavy fuel oil(heating oil/fuel oil/lubricating oil)
Catalytic cracking
1)Vaporise long-chain hydrocarbons by heating them.
2)The vapour is passed over a hot powdered aluminium oxide catalyst.
3) The long-chain molecules split apart on the surface of the specks of catalyst - this is catalytic cracking.
Steam cracking
You can crack hydrocarbons by vaporising them, mixing them with steam and heating them to a very high temperature.
Why is carbon monoxide dangerous
It’s a toxic chemical
It binds to the blood and reduces its ability to carry oxygen
Uses of short hydrocarbon molecules
To make alkenes and polymers
Difference in reactivity between alkenes and alkanes
Alkenes are more reactive than alkanes
In an investigation of the energy released by the combustion of hydrocarbon fuels, what black substance is at the bottom of the beaker?
Carbon soot
Displayed formula of methane
H
|
H- C- H
|
H
Gases formed in complete combustion of a hydrocarbon(test)
Carbon dioxide turns limewater cloudy
The water turns blue cobalt chloride paper pink
What happens to the carbon and hydrogen when it’s burned?
They’re oxidised
Volatility
How easily a substance vaporises
Why does viscosity increase with increasing hydrocarbon chain length?
It’s more difficult to separate/untangle larger masses when heated and convert them into a gas
Flammability
How easily a substance combusts
How does hydrocarbon chain length affect flammability?
Flammability decreases with increasing hydrocarbon chain length due to the large molecular masses making it difficult for oxygen to react with them at lower temperatures
Flames in alkanes
Small alkanes burn with a clean flame, but large alkanes burn with a smoky flame
Uses of bitumen fraction
Used for road surfacing and roofing/flooring
Products of incomplete combustion
Carbon monoxide, unburnt hydrocarbon and soot
How are nitrogen oxides formed?
Reaction of N2 in air with O2 in air at very high temperatures
Problems of nitrogen oxides
Acid rain
How is sulfur dioxide formed!
Combustion of sulfur(reaction with oxygen) in fuel
Problems of sulfur dioxide
Acid rain
Ways to reduce problem of sulfur dioxide
Remove sulfur from fuel before burning/remove sulfur dioxide from
fumes after burning(flue gas desulfurisation)
Ways to reduce problem of nitrogen oxides
For engines use a catalytic converter
Ways to reduce carbon monoxide problem
Ensure there’s a good supply of air/oxygen when burned
Problems of carbon
Blackens buildings
Global dimming
Formed: Incomplete combustion(reaction with oxygen) of carbon in fuel
How to reduce problem of carbon monoxide
Ensure there’s a good supply of air/oxygen when burned
Unburned fuel
Formed when not all fuel burns, harmful and a greenhouse gas,
ensure the correct fuel/air mixture when fuel is burned
What does sulfur dioxide react with in flue gas desulphurisation to be removed?
CaO or CaCO3
Problem of acid rain
Damages trees/plants
Respiratory problems
Damages buildings/statues
