POM 9.2.1 Flashcards by Stephanie Isabelle

Acid + Metal —> ?

Salt + Hydrogen gas

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Acid + Base —–> ?

Salt + Water

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Acid + Carbonate –> ?

Carbon dioxide gas + salt + water

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Cracking of PENTANE reaction

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

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

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Hydrogenation of ethylene

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

C2H4 (g) + H2 (g) –Pt–> C2H6 (g)

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Hydration of ethylene

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

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Dehydration of ethanol

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

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

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Fermentation of glucose

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

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

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Displacement of Cu from solution due to Zn

Zinc + copper sulfate –> zinc sulfate + copper

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

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Ionic equation of Cu and Zn displacement

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

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Net ionic equation for displacement of Cu from Zn

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

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

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Half-equations of displacement of Cu from Zn

Zn —> Zn 2+ + 2e-

- Cu 2+ + 2e- —> Cu

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Define an ALKANE

A hydrocarbon with only single bonds between the carbons

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Define an ALKENE

A hydrocarbon with 1 or more double bonds between carbons

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What is petroleum?

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

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

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

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What is the process of CRACKING?

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

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How is CRUDE OIL separated?

Fractional distillation

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Describe CATALYTIC CRACKING

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

Describe THERMAL (steam) CRACKING

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

Why is ETHYLENE highly reactive?

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

What are ADDITION reactions?

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’

What are the different types of addition reactions?

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

Describe POLYMERISATION

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

Differentiate between monomers and polymers

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

Why can ethylene undergo polymerisation?

Because of its reactive double bond

What is the monomer and polymer in ethylene

- Monomer: Ethylene | - Polymer: Polyethylene

Describe Addition polymerisation

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

Describe the high pressure method in the production of polyethylene

- 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

Describe the Ziegler-Natta Process in the production of polyethylene

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

What are the steps in the production of polyethylene?

- 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

Describe Vinyl Chloride and it's systematic name and formula

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

Describe Styrene and it's systematic name and formula

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

Use of LDPE in relation to its properties?

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

Use of HDPE in relation to its properties?

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

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

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

Use of Crystal Polystyrene in relation to its properties?

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

Use of Expanded Polystyrene in relation to its properties

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

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

Cyclohexene and cyclohexane

What was the conclusion of the bromine water experiment?

- 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

Formula for the bromine water experiment

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

Why was cyclohexene and cyclohexane used?

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

Limitations of the bromine water test?

The alkane reacted slightly as UV radiation caused slow substitution reactions

Safety precautions of the bromine water experiment

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

Limitations of the modelling of polymerisation practical

- 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