3.3.2-Alkanes

Question 1

What is petroleum

Answer 1

It is a complex mixture of hydrocarbons

Question 2

2 features of petroleum

Answer 2

Mainly alkanes which are hydrocarbons

When first extracted is almost useless

Question 3

How is petroleum separated

Answer 3

Fractional distillation

Question 4

3 key points of fractional distillation

Answer 4

Relies on hydrocarbon chains length being different so bp are different

Long chains have higher boiling point than short Chains

Long chains move toward bottom and short chains to top

Question 5

Uses of fractions

Answer 5

Fuels
Petrochemicals
Feedstock for cracking

Question 6

Why do we do cracking

Answer 6

There are a shortage of some chain length and a surplus of others as well alkenes are in high demand to make polymer which can only be found through cracking

Question 7

What does a high mr make after cracking

Answer 7

Small mr + alkenes + hydrogen

Question 8

What are the conditions of thermal cracking

Answer 8

High temperature 400-600

High pressure (7,000Kpa)

Question 9

What are the products of thermal cracking

Answer 9

Alkenes

Question 10

What are the uses of the products from thermal cracking

Answer 10

Chemical feedstock and conversion to polymers

Question 11

Thermal cracking
Conditions
Products
Uses

Answer 11

High temperature
High pressure

Alkenes

Chemical feedstock and conversion to polymers

Question 12

Catalytic cracking

Conditions

Answer 12

High temp -450
Slight pressure
Zeolite catalyst

Question 13

Products of catalytic cracking

Answer 13

Branched alkanes, cyclohexane, aromatic hydrocarbons

Question 14

Uses of products of catalytic cracking

Answer 14

Motor fuels

Question 15

Methane use when burned

Answer 15

Natural gas, cooking , heating , electric

Question 16

Combustion of propane uses

Answer 16

Camping fuel , domestic fuel and industrial fuel

Question 17

Combustion of butane uses

Answer 17

Camping fuel and lighters

Question 18

Uses of octane combustion

Answer 18

In petrol

Question 19

What is complete combustion conditions and products

Answer 19

Excess of oxygen

Products CO2 and H20

Question 20

What are conditions and products of incomplete combustion

Answer 20

Limited supply of oxygen
Products CO,C and H2O

CO is poisonous

Question 21

What are the the pollutant produced by car engines

Answer 21

CO

NOx

Unburnt hydrocarbons

Question 22

How is Co formed and the problem

Answer 22

Incomplete combustion

Poisonous gas

Question 23

How are NOx formed and the problem

Answer 23

N2 and O2 react at high temperatures in engine

Combine with water to make acid rain and chemical smog

Question 24

How NOx forms acid rain equation

Answer 24

4NO+O2+H2O - HNO3

Question 25

How does NOx form chemical smog equation

Answer 25

4NO+O2+2H2O - 4HNO3

Question 26

How are unburnt hydrocarbons formed and the problem

Answer 26

Engine not hot enough Makes photochemical smog irritating to lungs

Question 27

What is a catalytic converter

Answer 27

Catalytic converters are honeycomb of ceramic material coated with catalytic metals in thin layers

Question 28

Examples of catalysts

Answer 28

Platinum, palladium , rhodium

Question 29

How is NOx and CO changed to harmless gas in catalytic converter

Answer 29

NOx C Adsorb onto catalyst and react to form N2 and CO2 2NO+2CO- N2 +2CO2 NO2 +4CO - N2 + 4CO2

Question 30

How do unburnt hydrocarbons change to unharmful compounds

Answer 30

React with NO to produce CO2 and H20 and N2 C8H18+25NO-8CO2+9H2O+12.5H2O

Question 31

What happens when fossil fuels contain sulphur

Answer 31

S+O2 burns to make SO2 This goes into the air

Question 32

What is the problem with SO2

Answer 32

SO2 in the air with water forms H2SO3 which is acid rain

Question 33

How do you remove SO2

Answer 33

FGD(flue gas desulphisers) Passed through CaO SO2+ CaO--CaSO3 Oxidised CaSO3+1/2O2 -- CaSO4

Question 34

How can CaSO4 be used after it is formed

Answer 34

Can be used as gypsum in plaster

Question 35

What are the greenhouse gases

Answer 35

Carbon dioxide Methane Water

Question 36

What do the greenhouse gases do

Answer 36

Absorb some of infa-red energy Molecules then emit energy in all directions Some returns to surface to keep warm

Question 37

Impact of global warming

Answer 37

Ice in polar regions are melting and retreating | Sea levels rising