3.2 Alkanes

Question 1

How is boiling point of alkanes affected by chain length

Answer 1

Question 2

How is boiling point of alkanes affected by number of branches

Answer 2

Question 3

Define a fraction

Answer 3

A mixture of compounds with similar boiling points and similar sized molecules

Question 4

What are the features of fractional distillation that enable crude oil to be separated into fractions

Answer 4

Question 5

What is the purpose of cracking

Answer 5

To break larger fractions into smaller fractions
To produce a greater number of alkenes

Question 6

Properties of thermal cracking

Answer 6

High temperature and high pressure

Question 7

What is the purpose of catalytic cracking and state it’s properties

Answer 7

Produces a high percentage of branches alkanes and cycloalkanes
Properties :
- high temperature
- slight pressure
- catalyst : zeolite

Question 8

What compounds lead to greenhouse gas

Answer 8

CO2 & H2O & CH4

Question 9

How is acid rain formed

Answer 9

Question 10

How do you get rid of sulfur dioxide

Answer 10

Question 11

What is a catalytic converter

Answer 11

A honeycomb structure which are made of platinum and rodium metals - which are the catalysts
- they are designed to convert harmful gases into less harmful ones
- a honeycomb structure increases surface area, increasing rate of reactions

Question 12

Draw the equipment of fractional distillation

Answer 12

Question 13

Economic reasons for cracking

Answer 13

Question 14

What is the mechanism of greenhouse effect

Answer 14

Question 15

Answer 15

Fractional distillation
To seperate naptha from other compounds / to seperate them by chain length / size / boiling point

Question 16

Give meaning of term saturated and hydrocarbon as applied to saturated hydrocarbons

Answer 16

Saturdated - Single bonds only
Hydrocarbons - contains carbon and hydrogen atoms only

Question 17

Answer 17

Crude oil
Fractional distillation

Question 18

Answer 18

a) fractional distillation
b) C4H10, because it has a higher boiling point / longer chain / stronger IMF

Question 19

Answer 19

2-2-dimethylpropane
ii) because molecule is smaller
Van de Waals forces between molecules are weaker

Question 20

Answer 20

Different boiling points

Question 21

Answer 21

Shows gradual change in physical properties
Differ by CH2
Chemically similar / react in the same way
Have same functional group

Question 22

Name homologous series that both CH2 and C2H4 both belong to

Answer 22

Alkenes

Question 23

Answer 23

I) C16H34
ii) Diesel, Fuel oil, lubricant

Question 24

Explain how oxides of nitrogen are formed in engines

Answer 24

Reaction of nitrogen and oxygen in the air
At high temperatures

Question 25

Why is it desirable to decrease emissions of oxides of nitrogen from vehicles

Answer 25

Formation of acid rain / causes respiratory problems

Question 26

Equation that removes nitrogen monoxide in a catalytic converter

Answer 26

2 NO + 2 CO -> N2 + 2CO2

Question 27

Suggest how partial blockage might affect performance helicopter engine

Answer 27

Less energy given out as fuel Engine is less powerful

Question 28

Why combustion of fuel oil is likely to be incomplete

Answer 28

Difficult to supply oxygen / air for complete combustion

Question 29

Gas that may be present because of incomplete combustion Why use of electrostatic precipitators could be a hazard if this gas were present

Answer 29

Carbon monoxide Flammable

Question 30

Answer 30

Less chance of reaction of SO2 If flow is fast

Question 31

Answer 31

To reduce amount of metals needed To give catalyst larger surface area

Question 32

Answer 32

On combustion SO2 produced which causes acid rain

Question 33

Why is NO a pollutant gas

Answer 33

Contributes to global warming / formation of acid rain

Question 34

Why does calcium oxide react with Sulfur dioxide Why if calcium oxide coated on a mesh

Answer 34

It is basic / SO2 is acidic Bigger surface area to react

Question 35

Answer 35

Question 36

Answer 36

In thermal cracking, large hydrocarbons are broken down into smaller, more useful molecules - often alkenes, which have a region of high electron density due to their double bonds, making them reactive towards electrophiles. So you can draw any one of these structures : But-1-ene But-2-ene 2-methylpropene

Question 37

Answer 37

Question 38

Answer 38

Question 39

Answer 39

Question 40

Answer 40

Question 41

Answer 41

To provide enough energy to break chlorine bonds

Question 42

Answer 42

Question 43

Answer 43

C

Question 44

Answer 44

C

Question 45

Answer 45

D

Question 46

Answer 46

Question 47

Answer 47

Final answer : 0.008 + 0.0075 = 0.0155

Question 48

How is Nitrogen Monoxide removed from exhaust gases formed in petrol-fueled cars

Answer 48

Catalytic converter