Crude oil, hydrocarbons and alkanes.

Question 1

What is crude oil

Answer 1

A finite resource consisting mainly of plankton that was buried in the mud- crude oil is the remains of ancient biomass formed in covalent bonds.

Question 2

What are hydrocarbons

Answer 2

These are compounds made of hydrogen and carbon, they make up the majority of the compounds in crude oil and most of them are alkanes.

Question 3

What is the general formula for alkanes

Answer 3

CnH2n+2

Question 4

How are alkanes formed?

Answer 4

The cracking of longer chained alkanes.

Question 5

What is methanes chemical configuration

Answer 5

CH4

Question 6

What is ethane’s chemical configuration?

Answer 6

C2H6

Question 7

What is propanes chemical configuration?

Answer 7

C3H8

Question 8

What is butane’s chemical configuration?

Answer 8

C4H10

Question 9

What are alkenes

Answer 9

Alkenes are hydrocarbons with a double bond (some formed during the cracking process)

Question 10

State the test for alkenes and properties.

Answer 10

Alkenes are more reactive than alkanes and react with bromine water. Bromine water changes from orange to colourless in the presence of alkenes.

Question 11

What are fractions?

Answer 11

The hydrocarbons in crude oil split into fractions. Each fraction contains molecules with a similar number of carbon atoms in them, all fractions have different boiling points. This process is fractional distillation.

Question 12

What are the fractions used as?

Answer 12

Fractions can be processed to produce fuels and feedstock for petrochemical industry.

Question 13

State examples of fractional distillation fuels

Answer 13

Kerosene, petrol diesel etc

Question 14

State 3 examples of useful materials made by the petrochemical industry

Answer 14

Solvents, lubricants, polymers.

Question 15

What is cracking

Answer 15

The breaking of long chain hydrocarbons into the smaller chains. The smaller chains are more useful and can be done by either catalytic cracking steam cracking.

Question 16

What is catalytic cracking?

Answer 16

The heavy fraction is heated until vaporised. After vaporisation, the vapour is passed over a hot catalyst in a cracker forming smaller, more useful hydrocarbons.

Question 17

What is steam cracking?

Answer 17

The heavy fraction is heated until vaporised. After vaporisation, the vapour is mixed with steam in a cracker and heated to a very high temperature forming small, more useful hydrocarbons.

Question 18

What 3 alkenes/alkanes form decane?

Answer 18

Pentane, propene, ethane

Question 19

What are alkenes used to produce?

Answer 19

They produce polymers and also used as the starting materials of many other chemicals, such as alcohol, plastics and detergents.

Question 20

Why do we crack king hydrocarbon chains?

Answer 20

Without cracking, many of the long hydrocarbons would be wasted as there is not much demand for these as for the shorter chains.

Question 21

What is the word equation for complete combustion

Answer 21

Oxygen + alkane (ethane) = water + carbon dioxide + energy

Question 22

What is the word equation for incomplete combustion?

Answer 22

Alkane (ethane) + oxygen = carbon + carbon monoxide + water + energy

Question 23

What is the equation for alkenes

Answer 23

CnH2n

Question 24

What does crude oil need in order to be formed ( 5 things)

Answer 24

The remains of dead animals / plants - plankton and algae
No oxygen
High temperatures
High pressures - layers of sand/dirt/rock
Millions of years

Question 25

What is meant by the term ‘homologous series’

Answer 25

A collection of compounds with the same general formula that differ only in the carbon chain length.

Question 26

Differences between alkanes / alkenes

Answer 26

Alkanes
-no double bonds
-saturated
-less reactive
Alkenes
-double bond (only one)
-unsaturated
-more reactive

Question 27

What does saturated mean?

Answer 27

Only single bonds and bonds cannot be broken.

Question 28

As the molecule increases, the boiling point..

Answer 28

Increases

Question 29

As the molecule increases, the volatility (cleaner flame)….

Answer 29

Decreases, larger molecules have more of an unclean flame

Question 30

As the molecule increases, the viscosity..

Answer 30

Also increases (more easier to flow)

Question 31

As the molecule increases, the flammability..

Answer 31

Decreases

Question 32

State the 5 steps to the separation of crude oil in fractional distillation.

Answer 32

1. Crude oil is heated until vaporised in a furnace around 400degrees
   2.the vapour enters the column
   3.the column is hotter at the bottom and cooler at the top
   4.hydrocarbons condense at different temperatures, depending on their boiling points,
   5.large hydrocarbons have higher boiling points as they have move intermolecular forces within their atoms, meaning the bonds are harder to break which requires more energy.

Question 33

State uses of petroleum

Answer 33

Stored in canisters that can be used to heat food in barbecues / caravans. It’s cheap but also expensive.

Question 34

State uses of petrol.

Answer 34

This fuels cars, it is less expensive than diesel and petrol cars cannot run on diesel. (Smaller vehicles)

Question 35

State uses of kerosene

Answer 35

Fuels jet engines for planes and is very expensive

Question 36

State uses of diesel

Answer 36

This is more expensive than petrol and it fuels cars. Diesel cars cannot run on petrol.

Question 37

State uses of residue. (Lubricating oil, paraffin wax and bitumen)

Answer 37

Leftovers, quite cheap used for tea on roads and seals roofs.

Question 38

State differences between the two combustions (incomplete / complete)

Answer 38

Complete
- unlimited supply of oxygen
- ‘clean’ combustion
-hydrocarbon burnt out completely leaving products water and carbon dioxide.
-burning candle wax
Incomplete
-lack of oxygen
-‘dirty’ combustion
-hydrocarbon is not burnt out fully, forming carbon, carbon monoxide and water,

Question 39

State examples of incomplete combustion

Answer 39

Burning wood
Burning fossil fuels.