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GCSE Chemistry > Organic chemistry - crude oil, hydrocarbon properties, alkanes, fractional distillation, combustion > Flashcards

Organic chemistry - crude oil, hydrocarbon properties, alkanes, fractional distillation, combustion Flashcards

1
Q

Describe how crude oil is formed

A

Crude oil is a finite resource (if we continue using it then crude oil will one day run out) found in rocks.

Crude oil is formed over millions of years from the remains of an ancient biomass consisting mainly of plankton that was buried in mud

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2
Q

where is crude oil found

A

crude oil is found in rocks

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3
Q

what type of resource is crude oil

A

crude oil is a finite resource

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4
Q

what is an energy resource

A

An energy resource is anything that we use to obtain energy

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5
Q

what is a renewable resource

A

A renewable energy resource is one that can be replenished as it is being used and therefore will not run out

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6
Q

what is a finite resource

A

A non-renewable energy resource is one that cannot be replenished in a short enough time period and therefore will run out

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7
Q

Crude oil is a mixture of molecules called ________

A

hydrocarbons

Crude oil is a mixture of a very large number of compounds. Most of
the compounds in crude oil are hydrocarbons

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8
Q

describe structure of methane

A

contains one carbon atom covalently bonded to four hydrogen atoms

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9
Q

Describe what is meant by a hydrocarbon

A

Hydrocarbons are molecules made up of hydrogen and carbon atoms only

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10
Q

General formula of alkanes

A

Alkanes have the general formula CnH2n+2

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11
Q

name first four alkanes, state their molecular formulas and draw their their displayed formulas, and their structural formulas

A

Methane - 1 CH4
Ethane - 2 C2H6
Propane -3 C3H8
Butane -4 C4H10

displayed = h-c-h etc.
structural - groups of atoms ch3ch3 for ethane

https://bam.files.bbci.co.uk/bam/live/content/zskfk2p/medium

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12
Q

Explain why alkanes are said to be saturated molecules

A

Alkanes are saturated molecules
That is because the carbon atoms are fully bonded to hydrogen atoms

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13
Q

Describe what is meant by an alkane

A

a saturated hydrocarbon with the general formula CnH2n+2

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14
Q

properties of hydrocarbons

A

Viscosity
Flammability
Boiling point

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15
Q

properties of short chain hydrocarbons

A

low viscosity
highly flammable
low boiling point

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16
Q

properties of long chain hydrocarbons

A

high Viscosity
low Flammability
high Boiling point

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17
Q

What is viscosity

A

Viscosity tells us the thickness of a fluid
Fluids with a high viscosity flow slowly

18
Q

Describe how viscosity of hydrocarbons depend on the size of their molecules

A

As the size of the hydrocarbon molecule increases, the molecules get more viscous

Very long chain hydrocarbons flow very slowly
Long chain hydrocarbons are extremely viscous

19
Q

What is flammability

A

Flammability tells us how easily a hydrocarbon combusts (burns)

20
Q

Describe how flammability of hydrocarbons depend on the size of their molecules

A

As the size of the hydrocarbon molecule increases, the molecules get less flammable

Short chain hydrocarbons are extremely flammable
Long chain hydrocarbons are very difficult to burn

21
Q

What is the boiling point

A

The boiling point is the temperature at which a liquid turns to a gas

22
Q

Describe how the boiling point of hydrocarbons depend on the size of their molecules

A

As the size of the hydrocarbon molecule increases, the boiling point also increases.

Short chain hydrocarbons have low boiling points
(first four alkanes are gases at room temperature)
Very long chain hydrocarbons have very high boiling points

23
Q

The first four alkanes are gases at room temperature
What does this tell us about their boiling point

A

Short chain hydrocarbons have low boiling points
(first four alkanes are gases at room temperature)
this is because they all have boiling points which are lower than room temperature

24
Q

Describe how hydrocarbons can be used as fuels

A

Hydrocarbon fuels release energy when combusted (burned)

HYDROCARBONS ARE USED AS FUELS DUE TO THE AMOUNT OF ENERGY RELEASED WHEN THEY COMBUST COMPLETELY
LOTS OF ENERGY

25
Q

ships, planes and cars all run on____________

A

hydrocarbon fuels

26
Q

What happens to hydrocarbon fuels when they combust (burn)

A

Hydrocarbon fuels release energy when combusted (burned)

27
Q

Describe what happens during combustion of a hydrocarbon fuel

A

During combustion, the carbon and hydrogen atoms in the (hydrocarbon) fuel react with oxygen.
The carbon and hydrogen are oxidised

28
Q

During the combustion of a hydrocarbon fuel if the oxygen is unlimited what is produced

A

During the combustion of a hydrocarbon fuel if the oxygen is unlimited, this reaction produces carbon dioxide and water. This is called complete combustion

29
Q

What does the complete combustion of a hydrocarbon produce

A

The complete combustion of a hydrocarbon produces carbon dioxide
and water

30
Q

what is complete combustion of a hydrocarbon fuel

A

During combustion, the carbon and hydrogen atoms in the (hydrocarbon) fuel react with oxygen.
The carbon and hydrogen are fully oxidised - and the products/produces co2 + water

31
Q

Write balanced equations for the complete combustion of methane

A

methane + oxygen -> carbon dioxide + water
CH4 + 2O2 —-> CO2 + 2H2O

32
Q

Describe how the hydrocarbons in crude oil can be separated by fractional distillation

A

Firstly, the crude oil is heated to a very high temperature
This causes the crude oil to boil. All of the hydrocarbons evaporate and turn into a gas

The crude oil vapour is now fed into the fractional distillation column
The column is hotter at the bottom and cooler at the top

The hydrocarbon vapours now rise up the column
Hydrocarbons condense (turn back to a liquid) when they reach their boiling point

The liquid fractions are then removed

The remaining hydrocarbons continue moving up the column
These now condense when they reach their boiling points

Very long chain hydrocarbons have very high boiling points
These hydrocarbons are removed from the bottom of the column

Very short chain hydrocarbons have low boiling points
These do not condense
They are removed from the top of the column as gases

33
Q

State the functions of the important fractions

A

The fractions can be processed to produce fuels and feedstock for the petrochemical industry.

Some fractions are used as fuels.
E.G. Petrol and diesel are used to fuel cars
kerosene is used as jet fuel
heavy fuel oil is used to power ships
liquified petroleum gas is used in camping stoves

Some fractions are used as feedstock for the petrochemical industry
A feedstock is a chemical that is used to make other chemicals
Feedstock fractions are used to make solvents, lubricants, detergents, polymers

34
Q

each hydrocarbon has a different

A

boiling point

35
Q

difference in boiling point between longer chain hydrocarbons and shorter chain hydrocarbons

A

Longer chain hydrocarbons have a higher boiling point than shorter chains

36
Q

What must be done in order for the hydrocarbons in crude oil to be useful

A

In order for the hydrocarbons in crude oil to be useful, we have to separate them

37
Q

The name of the technique used to separate hydrocarbons in crude oil

A

In order for the hydrocarbons in crude oil to be useful, we have to separate them
To do that, we use a technique called fractional distillation

38
Q

In fractional distillation what is the crude oil separated into

A

In fractional distillation, crude oil is separated into fractions

39
Q

What are fractions
What do fractions contain

A

Fractions contain hydrocarbons with a similar number of carbon atoms

40
Q

Where are long chain hydrocarbons removed and why

A

Very long chain hydrocarbons have very high boiling points
These hydrocarbons are removed from the bottom of the column

41
Q

Where are short chain hydrocarbons removed, why, and in what state and why

A

Very short chain hydrocarbons have low boiling points
These do not condense
They are removed from the top of the column as gases

42
Q

What does fractional distillation produce

A

Fractional distillation produces fractions

GCSE Chemistry (43 decks)

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