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

Question 1

Describe how crude oil is formed

Answer 1

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

Question 2

where is crude oil found

Answer 2

crude oil is found in rocks

Question 3

what type of resource is crude oil

Answer 3

crude oil is a finite resource

Question 4

what is an energy resource

Answer 4

An energy resource is anything that we use to obtain energy

Question 5

what is a renewable resource

Answer 5

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

Question 6

what is a finite resource

Answer 6

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

Question 7

Crude oil is a mixture of molecules called ________

Answer 7

hydrocarbons

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

Question 8

describe structure of methane

Answer 8

contains one carbon atom covalently bonded to four hydrogen atoms

Question 9

Describe what is meant by a hydrocarbon

Answer 9

Hydrocarbons are molecules made up of hydrogen and carbon atoms only

Question 10

General formula of alkanes

Answer 10

Alkanes have the general formula CnH2n+2

Question 11

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

Answer 11

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

Question 12

Explain why alkanes are said to be saturated molecules

Answer 12

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

Question 13

Describe what is meant by an alkane

Answer 13

a saturated hydrocarbon with the general formula CnH2n+2

Question 14

properties of hydrocarbons

Answer 14

Viscosity
Flammability
Boiling point

Question 15

properties of short chain hydrocarbons

Answer 15

low viscosity
highly flammable
low boiling point

Question 16

properties of long chain hydrocarbons

Answer 16

high Viscosity
low Flammability
high Boiling point

Question 17

What is viscosity

Answer 17

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

Question 18

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

Answer 18

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

Question 19

What is flammability

Answer 19

Flammability tells us how easily a hydrocarbon combusts (burns)

Question 20

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

Answer 20

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

Question 21

What is the boiling point

Answer 21

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

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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

Question 24

Describe how hydrocarbons can be used as fuels

Answer 24

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

Question 25

ships, planes and cars all run on____________

Answer 25

hydrocarbon fuels

Question 26

What happens to hydrocarbon fuels when they combust (burn)

Answer 26

Hydrocarbon fuels release energy when combusted (burned)

Question 27

Describe what happens during combustion of a hydrocarbon fuel

Answer 27

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

Question 28

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

Answer 28

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

Question 29

What does the complete combustion of a hydrocarbon produce

Answer 29

The complete combustion of a hydrocarbon produces carbon dioxide and water

Question 30

what is complete combustion of a hydrocarbon fuel

Answer 30

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

Question 31

Write balanced equations for the complete combustion of methane

Answer 31

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

Question 32

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

Answer 32

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

Question 33

State the functions of the important fractions

Answer 33

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

Question 34

each hydrocarbon has a different

Answer 34

boiling point

Question 35

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

Answer 35

Longer chain hydrocarbons have a higher boiling point than shorter chains

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

In fractional distillation what is the crude oil separated into

Answer 38

In fractional distillation, crude oil is separated into fractions

Question 39

What are fractions What do fractions contain

Answer 39

Fractions contain hydrocarbons with a similar number of carbon atoms

Question 40

Where are long chain hydrocarbons removed and why

Answer 40

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

Question 41

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

Answer 41

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

Question 42

What does fractional distillation produce

Answer 42

Fractional distillation produces fractions