Alkanes

Question 1

What is the general formula of alkanes?

Answer 1

CnH2n+2

Question 2

Give the formula for pentane

Answer 2

C5H12

Question 3

What are some uses of Naptha?

Answer 3

Petrochemicals

Question 4

State some uses of kerosene

Answer 4

Jet fuel, petrochemicals

Question 5

What crude oil fraction is used as diesel fuel?

Answer 5

Gas oil

Question 6

What is heavy fuel oil used for?

Answer 6

Ships, power stations

Question 7

Name the crude oil fraction that is used for candles

Answer 7

Wax, grease

Question 8

Which type of cracking uses a zeolite catalyst?

Answer 8

Catalytic cracking

Question 9

Which type of cracking produces mainly alkenes?

Answer 9

Thermal Cracking

Question 10

Give the conditions required for thermal cracking

Answer 10

1000*C
70 atm

Question 11

State the conditions of catalytic cracking

Answer 11

Slight Pressure
500*C

Question 12

Name the type of hydrocarbon produced in catalytic cracking

Answer 12

Aromatic Hydrocarbons

Question 13

Give 2 advantages of catalytic cracking

Answer 13

Faster, cheaper

Question 14

What is the metal used for catalytic cracking of alkanes?

Answer 14

Zeolite

Question 15

Which type of cracking produces aromatic hydrocarbons?

Answer 15

Catalytic cracking

Question 16

Give 2 products produced during incomplete combustion that aren’t produced in complete combustion

Answer 16

• Particulate carbon
• Carbon Monoxide

Question 17

What is needed for complete combustion to occur?

Answer 17

Excess of O2

Question 18

How is carbon monoxide harmful to the human body?

Answer 18

• Binds to haemoglobin on RBC
• Diminishes O2 supply

Question 19

How can harmful gases be removed from exhaust gases?

Answer 19

Using catalytic convertors

Question 20

Give 2 problems with the production of particulate carbon

Answer 20

• Respiratory Problems
• Build ups in engines prevent them from functioning

Question 21

Are oxides of nitrogen poisonous?

Answer 21

Yes, and very toxic

Question 22

How is nitrogen monoxide produced in car engines?

Answer 22

• High pressure and temperature
• Causes nitrogen and oxygen atoms to react

Question 23

How are unburnt hydrocarbons harmful?

Answer 23

• They react in sunlight to form ground-level ozone
• Ozone is very harmful

Question 24

Give 3 things that catalytic convertors remove from exhaust gases

Answer 24

• Carbon Monoxide
• Unburnt hydrocarbons
• Nitrogen Oxides

Question 25

How is SO2 created?

Answer 25

During the burning of sulfur

Question 26

How can sulfur dioxide cause acid rain?

Answer 26

- By dissolving into moisture - Sulfuric Acid is created

Question 27

How can sulfur be removed from flue gases?

Answer 27

- By mixing powdered CaO with water and adding to gases - Sulfur Dioxide neutralises - Harmless Calcium sulfite formed

Question 28

What is a free radical?

Answer 28

A particle with an unpaired electron

Question 29

How do free radicals form?

Answer 29

When a covalent bond splits equally

Question 30

Why are free radicals so reactive?

Answer 30

They have an unpaired electron

Question 31

Give the equation for the synthesis of chloromethane

Answer 31

CH4 + Cl2 ---> CH3Cl + HCl

Question 32

What occurs in the initiation step of free radical substitution?

Answer 32

- 2 free radicals are produced - Covalent bond splits equally

Question 33

Give an example of an initiation step involving Cl2

Answer 33

Cl2 --> 2Cl*

Question 34

What occurs in the 2 propagation steps?

Answer 34

- Free radicals are used up and created

Question 35

What occurs in the termination step of free radical substitution?

Answer 35

- Free radicals are used up to make a stable molecule

Question 36

What is a chlorofluorocarbon?

Answer 36

- A halogenoalkane - All C atoms are replaced by either F or Cl atoms

Question 37

How does ozone in the upper atmosphere act as a chemical sunscreen?

Answer 37

By absorbing lots of UV from the sun

Question 38

Give two risks of exposure to UV light

Answer 38

Sunburn, skin cancer

Question 39

How do CFC's damage the atmosphere?

Answer 39

- Cl* radicals are formed - Radicals act as catalysts and react with O3

Question 40

Describe how the chain reaction between Cl* radicals and ozone occurs

Answer 40

Cl* radical is regenerated and goes on to attack another molecule

Question 41

State 3 properties of CFC's

Answer 41

Unreactive, non-flammable and non-toxic

Question 42

Name how CFC's were used before their problems were discovered

Answer 42

- Coolants in fridges - Propellants - Fire extinguishers

Question 43

What is the new, safer alternative to CFC's?

Answer 43

HCFC's, hydrochlorofluorocarbons

Question 45

What is a haloalkane?

Answer 45

An alkane with at least one halogen atom instead of a hydrogen atom

Question 46

What is a halogenoalkane?

Answer 46

An alkane with at least one halogen atom replacing a hydrogen atom.

Question 47

Explain why most C-halogen bonds are polar

Answer 47

Halogens are very electronegative

Question 48

What is a nucleophile?

Answer 48

Electron-pair donor; loves positive charge

Question 49

Which atom contains the lone pair in a cyanide ion?

Answer 49

Carbon

Question 50

Name three nucleophiles

Answer 50

- Cyanide ions - Ammonia - Hydroxide ions

Question 51

Summarise the events of a nucleophillic substitution reaction

Answer 51

- Nucleophile attacks polar molecules - Kicks out functional group - Nucleophile replaces halogen

Question 52

What do halogen produce when reacted with hydroxide ions?

Answer 52

Alcohols

Question 53

What two substances react to produce nitriles?

Answer 53

Haloalkanes, cyanide ions

Question 54

What is produced when halogens react with ammonia?

Answer 54

Amines

Question 55

Why are ethanolic conditions used when making nitriles or amines?

Answer 55

To prevent formation of alcohols

Question 56

What is the functional group of amines?

Answer 56

NH2

Question 57

What is formed as a waste product during formation of amines?

Answer 57

Ammonium ions

Question 58

What is needed to remove a hydrogen atom from the NH3 group during nucleophillic substitution?

Answer 58

Another ammonia atom (nucleophile)

Question 59

Which type of halogenoalkane reacts slowest during nucleophillic substitution?

Answer 59

Fluoroalkanes, contain strongest bond

Question 60

Which haloalkanes undergoes nucleophillic substitution quickest?

Answer 60

Iodoalkanes

Question 61

What is formed in elimination reactions?

Answer 61

Alkene