Chapter 13 (Alkenes) Flashcards

1
Q

What is the reactivity of alkenes ?

A
  • more reactive than alkanes due to pi bond
  • C=C is made up of a sigma and a pi bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens in alkene addition reactions ?

A

small molecule added across the double bond, pi bond breaks, new bond forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens in the hydrogenation of alkenes ?

A
  • Alkene + hydrogen + (nickel catalyst) -> Alkane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens in halogenation ?

A
  • Br2 or Cl2 is added to alkene to form haloalkane
  • F2 is too reactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens in the addition of hydrogen halides ?

A
  • alkenes reacts with hydrogen halide dissolved in water to also form haloalkane
  • if alkene is liquid then hydrogen halide is bubbled through
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the differences between symmetrical and unsymmetrical products ?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens in the hydration of alkenes ?

A
  • alkene + water(steam) + (phosphoric acid) -> alcohol
  • this can form symmetrical and unsymmetrical products.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is an electrophilic addition reaction ?

A
  • the double bond in an alkene represents a region of high electron density due to pi electrons
  • high electron density attracts electrophiles
  • electrophile - an atom that is attracted to an electron rich centre and accepts an electron pair, usually positive ions, or molecule with a partial + charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the mechanism of electrophilic addition look like ?

A
  • the + carbon is a carbocation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the mechanism for bromination ?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an addition polymer ?

A

These are composed of a repeating pattern of a single monomer, no other products are produced in the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of monomers does addition polymerisation use ?

A

-unsaturated alkenes undergo addition polymerisation
- produces long saturated chains containing, NO double bonds
- carried out at high temperatures and high pressure
- ethane -> poly(ethene)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you represent addition polymers ?

A
  • the repeated unit is written in square brackets
  • after the bracket write a n to show a large number of repeats
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the difference between HDPE and LDPE ?

A
  • HDPE have less branching meaning they can get closer to each other meaning there are stronger london forces, meaning they have relatively high melting and boiling points
  • LDPE have lists of branching so can’t get closer to each to each other meaning weaker London forces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the uses of polymers ?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the environmental impact of polymers ?

17
Q

How can polymers be used as fuels ?

18
Q

What are biodegradable and photodegradable polymers ?

19
Q

why do alkenes display stereoisomerism ?

A
  • the functional groups are attatched to the C=C meaning the carbons remain fixed in their position, this is because free rotation of the bonds about C=C is not possible due to the presence of a π bond
20
Q

what is cis/trans isomerism ?

A
  • cis-trans isomerism is a special case of E/Z isomerism
  • 1 of the attatched groups on each C=C must be hydrogen
  • Cis: H atoms on the same side (Z)
  • trans: H atoms diagonally oposite(E)
21
Q

what is EZ isomerism ?

A
  • atoms / groups are given prority based on their atomic number
  • if the groups with higher priority are on the same side of the C=C then it is a Z-isomer
  • if the groups of higher priority are at a diagonal acrros the C=C then it is an E-isomer
22
Q

what is an example of working out E/Z isomerism ?