Crude oil and hydrocarbons

Question 1

what is an organic carbon compound

Answer 1

a compound that only contains carbon atoms

Question 2

what are organic compounds used for

Answer 2

run cars, warm homes and generate electricty

Question 3

formation of crude oil

Answer 3

1) tiny ancient sea animals and plants die and are buried in mud
2) layers of rock are then laid on top creating high pressure and temperature in the absence of oxygen
3) this forms fossil fuels, and then more layers of sand and mud fall on top of the fossils squishing them, and turning it into crude oil and natural gas
4) the oil and natural gas are pushed upwards by underground pressure and get stuck under caprock

Question 4

why isn’t crude oil from the ground useful

Answer 4

as it contains many different substances with different boiling points so it would have to be separated into fractions

Question 5

what is crude oil

Answer 5

a dark smelly liquid containing a mixture of carbon compounds

Question 6

what is a hydrocarbon

Answer 6

an organic carbon molecule containing only carbon and hydrogen atoms

Question 7

what are alkanes

Answer 7

saturated hydrocarbons with single-carbon covalent bonds

Question 8

why cant extra hydrogen atoms be added to alkanes

Answer 8

as they have single covalent bonds which means that they contain the maximum amount of hydrogen atoms on each molecule so no more hydrogen atoms can be added

Question 9

why are alkanes saturated

Answer 9

as the have single carbon covalent bonds

Question 10

formula for alkanes

Answer 10

CnH2n+2

Question 11

how many carbon atoms in methane

Answer 11

1

Question 12

how many carbon atoms in ethane

Answer 12

2

Question 13

how many carbon atoms in propane

Answer 13

3

Question 14

how many carbon atoms in butane

Answer 14

4

Question 15

how many carbon atoms in pentane

Answer 15

5

Question 16

what are fractions

Answer 16

a group of hydrocarbons with similar chain lengths

Question 17

characteristics of short chain hydrocarbons

Answer 17

• low boiling point
• high flammability
• low viscosity
• high volatility

Question 18

characteristics of long chain

Answer 18

• high boiling point
• high viscosity
• low flammability
• low volatility

Question 19

how is crude oil separated

Answer 19

• its separated into hydrocarbons with similar boiling points called fractions in the process of fractional distillation

Question 20

what does each hydrocarbon fraction contain

Answer 20

molecules with a similar number of carbon atoms, this causes the fractions to have different bp due to different sized molecules

Question 21

order from high boiling point to low bp of the different fuels found in a the crude oil distillation tower

Answer 21

refinery/ petroleum gas (used as fuel)
gasoline/ petrol (used in car engines)
kerosene (used as aircraft fuel)
diesel oil/ gas oil (fuel for diesel engines and boiler fuel)

Question 22

process of fractional distillation of crude oil

Answer 22

1) crude oil is heated
2) the oil is vaporised
3) the vapours move up the fractioning tower
4) the tower is kept very hot at the bottom and much cooler at the top so the temperature decreases going up the tower
5) different vapours condense at different heights and boiling points in the tower to create fractions
6) each fraction contains hydrocarbons of similar-sized molecules with similar boiling points
7) the crude oil is then separated into fractions with smaller hydrocarbons at the top as they have lower boiling points and larger hydrocarbons at the bottom as they have higher boiling points
8) once collected the fractions need more processing before they can be used

Question 23

what is the test for water

Answer 23

• anyhrdous copper sulfate will turn into blue hydrous copper sulfate when water is present (white powder turns into blue crystals)
• colbalt chloride paper turns from blue to pink when water is present

Question 24

what is produced in complete combustion

Answer 24

water and carbon dioxide

Question 25

what is produced in incomplete combustion

Answer 25

carbon monoxide

Question 26

why do we crack hydrocarbons

Answer 26

as they are made up of large molecules that are thick liquids or solids with high boiling points and are difficult to burn and vapourish so cannot be used as fuels

Question 27

what is cracking

Answer 27

breaking down larger useful hydrocarbons into smaller useful ones

Question 28

what happens in a cracker

Answer 28

heavy fractions from crude oil is distilled and heated to vaporise the hydrocarbons and the vapour is either passed over a hot catalyst or mixed with steam and heated to a very high temperature

Question 29

what type of reaction is cracking

Answer 29

thermal decomposition

Question 30

properties of alkenes

Answer 30

- unsaturated - methane cannot be an alkene as it only has 1 carbon atom - have double covalent bonds between carbon atoms

Question 31

what is the rule for a cracking formula

Answer 31

the total number of carbon and hydrogen atoms in the products has to be equal to the total number of carbon and hydrogen atoms in the reactants

Question 32

process of cracking

Answer 32

1) hydrocarbons with large molecules are heated until they turn into there vaporised state 2) hydrocarbons vapours are passed heated catalyst 3) thermal decompose hydrocarbons, until it forms hydrocarbons with small molecules

Question 33

conditions for cracking

Answer 33

- catalyst - high temperature and steam

Question 34

why are alkenes useful

Answer 34

- they are used to make polymers - they are used as the starting material for other chemicals - they are more reactive than alkanes

Question 35

test for alkene

Answer 35

- alkenes turn bromine water from orange to colourless

Question 36

why are alkenes unsaturated

Answer 36

as they have two fewer hydrocarbons than the alkane with the same number of carbon atoms

Question 37

what is the homologous series

Answer 37

a series of molecules with same functional group, each molecule in a homologous series have an extra carbon atom and two extra carbon atoms

Question 38

what is the alkene functional group

Answer 38

the double bond

Question 39

what is a functional group

Answer 39

the part of the molecule that determines how it reacts

Question 40

what occurs during hydrogenation (addition reaction)

Answer 40

there is an addition of the halogens to alkenes what do they form bromine - dibromo iodine - diodo chlorine - dichloro

Question 41

what occurs in hydration reaction (addition reactions)

Answer 41

there is an addition of water to alkenes

Question 42

conditions for hydration reactions

Answer 42

- the water must be stream - the temp must be 300 degrees Celsius - the pressure must be 70 atm (atmospheres) - phosphoric acid must be used as a catalyst

Question 43

dangers of the cracking experiment

Answer 43

- if the contents in the boiling tube is cooled during the experiment then the water will be sucked back into the boiling tube causing it to crack

Question 44

what to do if a suck back of water is detected in the cracking experiment

Answer 44

continue to heat the boiling tube with the hottest part of the flame and remove the boiling tube from the water