POM 9.2.1

Question 0

Acid + Metal —> ?

Answer 0

Salt + Hydrogen gas

Question 1

Acid + Base —–> ?

Answer 1

Salt + Water

Question 2

Acid + Carbonate –> ?

Answer 2

Carbon dioxide gas + salt + water

Question 3

Cracking of PENTANE reaction

Answer 3

Pentane (g) –energy–> ethylene (g) + propane (g)

C5H12 (g) –energy–> C2H4 (g) + C3H8 (g)

Question 4

Hydrogenation of ethylene

Answer 4

Ethylene (g) + Hydrogen (g) –Pt–> Ethane (g)

C2H4 (g) + H2 (g) –Pt–> C2H6 (g)

Question 5

Hydration of ethylene

Answer 5

Ethylene (g) + H2o (l) –H3PO4–> Ethanol (l)

Question 6

Dehydration of ethanol

Answer 6

Ethanol (l) –H2SO4–> Ethylene (g) + H2o (l)

C2H5OH (l) –H2SO4–> C2H4 (g) + H2o (l)

Question 7

Fermentation of glucose

Answer 7

Glucose (aq) –yeast–> ethanol (aq) + carbon dioxide (g)

C6H12O6 (aq) –yeast–> 2C2H5OH (aq) + 2CO2 (g)

Question 8

Displacement of Cu from solution due to Zn

Answer 8

Zinc + copper sulfate –> zinc sulfate + copper

Zn (s) + CuSO4 (aq) –> ZnSO4 (aq) + Cu (s)

Question 9

Ionic equation of Cu and Zn displacement

Answer 9

Zn + Cu (II) sulfate ion + Sulfate ion –> Zinc (II) ion + sulfate ion + Cu
Zn + Cu 2+ + SO4 2- –> Zn 2+ + SO4 2- + Cu

Question 10

Net ionic equation for displacement of Cu from Zn

Answer 10

Zinc + Copper (II) ion —> Zinc (II) ion + Copper

Zn (s) + Cu 2+ (aq) —> Zn 2+ (aq) + Cu (s)

Question 11

Half-equations of displacement of Cu from Zn

Answer 11

• Zn —> Zn 2+ + 2e-

- Cu 2+ + 2e- —> Cu

Question 12

Define an ALKANE

Answer 12

A hydrocarbon with only single bonds between the carbons

Question 13

Define an ALKENE

Answer 13

A hydrocarbon with 1 or more double bonds between carbons

Question 14

What is petroleum?

Answer 14

A complex mixture of hydrocarbons consisting mainly of alkanes and some alkenes

Question 15

What is Ethylene? What is it’s systematic name and formula?

Answer 15

• Systematic name: Ethene
• Formula: C2H4
• One of the most useful substances in the petrochemical industry
• High demand

Question 16

What is the process of CRACKING?

Answer 16

• The process of breaking large hydrocarbon molecules into smaller length chains, using heat (A)
• Catalytic cracking
• Thermal cracking

Question 17

How is CRUDE OIL separated?

Answer 17

Fractional distillation

Question 18

Describe CATALYTIC CRACKING

Answer 18

• Carried out in a “cat-cracker”
• Long ALKANE molecules (C15-C25) are broken into an ALKANE and an ALKENE
• Catalyst used: ZEOLITES
• Carried out at 500’C
• Absence of air
• Pressure above atmospheric pressure
• Uses less heat than thermal cracking but it is insufficient cause it can’t decompose large molecules completely

Question 19

Describe THERMAL (steam) CRACKING

Answer 19

• No catalyst
• Alkanes are decomposed COMPLETELY
• Long-chain alkanes passed through metal tubes at 700’C - 1000’C
• Pressure above atmospheric
• Use of steam allows easy flow of hydrocarbon gases and removes carbon desposits

Question 20

Why is ETHYLENE highly reactive?

Answer 20

• Ethylene has a highly reactive double-bond
• It is a site of high electron density
• One of the bonds readily breaks, creating 2 new bonding sites

Question 21

What are ADDITION reactions?

Answer 21

• A type of reaction ethylene can undergo

- One bond in the double bond is broken and two atoms in a DIATOMIC molecule are ‘added on’

Question 22

What are the different types of addition reactions?

Answer 22

• Hydrogenation: Ethylene + Hydrogen –Pt–> Ethane
• Hydration: Ethylene + Water –H3PO4–> Ethanol
• Halogenation: Reactive molecules from the halon group (Fl2, Cl2, Br2) can all react with ethylene

Question 23

Describe POLYMERISATION

Answer 23

The chemical reaction in which many identical small molecules combine to form one large molecule

Question 24

Differentiate between monomers and polymers

Answer 24

- Monomers are the small identical molecules | - A polymer is the large molecule formed from many monomers

Question 25

Why can ethylene undergo polymerisation?

Answer 25

Because of its reactive double bond

Question 26

What is the monomer and polymer in ethylene

Answer 26

- Monomer: Ethylene | - Polymer: Polyethylene

Question 27

Describe Addition polymerisation

Answer 27

- No additional molecules are produced - There is no gain/loss of atoms - The double bond simply 'opens' and monomers attach

Question 28

Describe the high pressure method in the production of polyethylene

Answer 28

- Ethylene subjected to pressures of 100-300MPa - Temperatures of 300'C - An initiator used (peroxide) - Creates UNBRANCHED chains of polyethylene which does not pack together tightly - LDPE

Question 29

Describe the Ziegler-Natta Process in the production of polyethylene

Answer 29

- A few atmospheres of pressure - Temperatures of 60'C - Catalyst used - Creates UNBRANCHED chains of polyethylene which pack together densely - HDPE

Question 30

What are the steps in the production of polyethylene?

Answer 30

- Initiation: the initiation molecule is added which reacts with one ethylene molecule, breaking the double bond and attaches to one bonding site, thus creating an ethylene initiator radical - Propagation: Another ethylene monomer attaches to this radical and this continues - Termination: The reaction stops when two such chains collide and the 2 radicals react, forming a longer chain

Question 31

Describe Vinyl Chloride and it's systematic name and formula

Answer 31

- Systematic name: Chloroethene - Formula: C2H3Cl - One hydrogen is substituted with a chlorine atom - Can form Polyvinyl Chloride

Question 32

Describe Styrene and it's systematic name and formula

Answer 32

- Systematic name: Phenylethene - Formula: C8H8 - One hydrogen atom replaced by a benzene ring - Forms Polystyrene

Question 33

Use of LDPE in relation to its properties?

Answer 33

Plastic cling wrap - it is flexible, clear and non-toxic

Question 34

Use of HDPE in relation to its properties?

Answer 34

Rubbish bins - it is rigid, only slightly flexible and hard

Question 35

Use of Polyvinyl Chloride (PVC) in relation to its properties?

Answer 35

Garden hoses - it can contain UV inhibitors, it's flexible and is relatively un-reactive

Question 36

Use of Crystal Polystyrene in relation to its properties?

Answer 36

CD cases - it is clear, hard, rigid, easily shaped and a good insulator

Question 37

Use of Expanded Polystyrene in relation to its properties

Answer 37

Disposable cups - it is light, cheap and a thermal insulator

Question 38

Which alkene and alkane were used to compare the reactivities of?

Answer 38

Cyclohexene and cyclohexane

Question 39

What was the conclusion of the bromine water experiment?

Answer 39

- Cyclohexene turned the brome water colourless - Cyclohexane solution remained yellow - Thus, only cyclohexene reacted and therefore the alkene is said to be more active due to the double bond

Question 40

Formula for the bromine water experiment

Answer 40

C6H10 (l) + Br2 (aq) + H2o (l) -----> C6h10BrOH (l) + HBr (aq)

Question 41

Why was cyclohexene and cyclohexane used?

Answer 41

- Ethylene/propene weren't used because C1 - C4 are gases at room temperature - hard to manage - Cyclohexene is liquid at room temperature

Question 42

Limitations of the bromine water test?

Answer 42

The alkane reacted slightly as UV radiation caused slow substitution reactions

Question 43

Safety precautions of the bromine water experiment

Answer 43

- cyclohexene/ane are poisonous if ingested and both give off fumes as they are highly volatile and flammable (use in fume cupboard)

Question 44

Limitations of the modelling of polymerisation practical

Answer 44

- The model only provided a limited section of a polyethylene molecule as there were limited numbers of kits - The use of catalysts were not shown in the process - therefore less accurate