Alkenes Flashcards

1
Q

Name two useful ways of disposing of polymers

A

Combustion for energy production; organic feedstock to make new plastics or other products

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2
Q

How are addition polymers made?

A

Poly(name of original alkene)

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3
Q

Reacting an alkene with bromine makes what?

A

A dibromo-alkane

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4
Q

What is the order of stability of primary, secondary and tertiary carbocations?

A

primary lowest secondary middle and tertiary highest. Tertiary > secondary > primary

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5
Q

Identify a hazard of burning PVC - poly(chloroethene)

A

Releases toxic HCL gas

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6
Q

When can you have cis/trans isomers as well as E/Z?

A

When one of the bonded substituents on each C is the same e.g. each has a Cl

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7
Q

Can double bonds rotate?

A

No- because pi bond would break if p orbitals not aligned

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8
Q

What is the shape and bond angle around the C atom in an alkene?

A

120 degrees, trigonal planar

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9
Q

How does stability of carbocation relate to the major and minor product in electrophilic addition of HX?

A

Major product is formed from the more stable carbocation

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10
Q

What is the structure of the repeat unit of poly(propene)

A

-CH2CH(CH3)-

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11
Q

What it added to an alkene to make an alcohol?

A

Steam, with acid catalyst - e.g. phosphoric acid

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12
Q

How does a pi bond form?

A

Sideways overlap of adjacent p orbitals above and below the bonding atoms.

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13
Q

What are the two requirements for E/Z isomerism?

A

C=C double bond, and two different groups bonded to each of the carbons.

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14
Q

What is Markownikoffs rule?

A

When HX reacts with an unsymmetrical alkene, the H bonds to the C of the alkene which has more H already bonded

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15
Q

Which monomer makes the polymer which has (CH2CHCl) as its repeat unit?

A

chloroethene

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16
Q

Name two types of sustainable polymers being formulated by chemists

A

Biodegradable and photodegradable polymers

17
Q

What is the test and positive result for an alkene

A

Decolourises bromine water

18
Q

In the electrophilic addition mechanism, what type of fission does the pi bond undergo?

A

Heterolytic fission - to form ions

19
Q

Describe a C=C double bond

A

One sigma bond and one pi bond

20
Q

Reacting ethene with hydrogen and Ni catalyst makes what?

A

Ethane

21
Q

How do the Cahn-Ingold-Prelog rules for identifying E/Z isomers assign priority?

A

Higher priority = higher atomic numbers

22
Q

Define an electrophile

A

An electron pair acceptor

23
Q

What type of mechanism do alkenes tend to react in e.g. with bromine

A

Electrophilic addition

24
Q

How can HCl gas from burning PVC be removed from waste mixture?

A

Neutralise with a base - e.g. sodium carbonate

25
Q

Why are alkenes more reactive than alkanes?

A

The pi bond has a relatively low bond enthalpy (compared to single sigma bonds)

26
Q

Define stereoisomers

A

Compounds with the same structural formula but different arrangements in space

27
Q

What are addition polymers formed from?

A

Alkenes and substituted alkenes

28
Q

Alkenes + HBr make what?

A

bromoalkane