Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-Level Chemistry > Chapter 13 - Alkenes > Flashcards

Chapter 13 - Alkenes Flashcards

1
Q

What makes up a double bond

A

sigma and pi bond

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

pi bond

A

sideways overlap of two p-orbitals
high electron density above and below the 2 bonding atoms

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

general formula

A

CnH2n

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

Bond angle and shape

A

120 & trigonal planar

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

Steroisomers

A

same structural formula but different arrangement of atoms in space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

E/Z isomerism conditions

A
  • double bond
  • different groups attached to each C in double bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

E isomer

A

grps in different direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Z isomer

A

grps in same direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Cis/trans isomerism

A

special E/Z isomerism where 1 grp attached to the carbon is the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Cahn-Ingold-Prelog rules

A

assigns priority based on atomic no.
higher the atomic no. higher the priority

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

why are alkenes more reactive then alkanes

A
  • due to pi bond - above and below sigma bond
  • as on outside pi bond more exposed allowing for more reactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

4 addition reactions

A
  • Hydrogenation
  • Halogenation
  • Hydrogen halides
  • Hydration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Hydrogenation

A
  • nickel catalyst
  • 423K
  • forms alkane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Halogenation

A
  • RTP
  • Forms haloalkane
  • can be used as test to see if double bond present
  • decolourises from orange to clear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hydrogen Halides

A
  • RTP
  • either as two gases or hydrogen halide bubbled through liquid alkene
  • forms haloalkane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Hydration

A
  • Steam
  • phosphoric acid catalyst
  • forms alcohol
17
Q

Electrophile

A
  • Electron pair acceptor
  • atom/grp of atoms that are attracted to electron-rich centres and can attract electron pair
  • positive ions or contains small partial positive charge
18
Q

Nucleophile

A
  • Electron pair donor
  • atom/grp of atoms that are attracted to electron-deficient centres and can donate an electron pair
  • negative ions or contains small partial negative charge
    e.g. alkenes which contain pi bonds
19
Q

mechanism

A

electrophilic addition

20
Q

electrophilic addition
reaction

A
  • hydrogen halide reaction
  • halogenation
21
Q

carbocation stability

A
  • increases as go from primary to tertiary
  • primary has one alkyl grp etc…
22
Q

carbocation stability explanation

A
  • each alkyl grp donates/ pushes electrons to positive charge of carbocation
  • more groups more evenly spread out and stable
23
Q

Markownikoff’s rule

A

when hydrogen halide reacts with unsymmetrical alkene, the H is attracted to the C atom with greater no. of H atoms and lower no. of C atoms

24
Q

Addition polymerisation

A
  • carried out by unsaturated alkenes to produce long saturated chains with no double bonds
  • usually high molecular masses
25
Q

addition polymerisation conditions

A
  • high temp
  • high pressure
  • usually catalyst (tin/nickel)
26
Q

environmental concerns

A
  • disposing of waste polymers
  • recycling
  • PVC recycling
  • polymers as waste fuels
  • feedstock recycling
  • bioplastics
  • biodegradable polymers
  • photodegradable polymers
27
Q

disposing of waste polymers

A
  • cheap and convenient to use
  • unreactive - good for storing food etc.. but means usually not biodegradable
  • harm marine life
  • usually from crude oil - non-renewable
28
Q

recycling

A
  • conserves fossil fuels
  • but have to be sorted by type (polymer content)
  • chopped, washed, dried, melted for resue
29
Q

PVC recycling

A
  • hazardous - high Cl and other additives content
  • releases toxic gases & dioxins when burnt
  • use solvent to dissolve polymer then recover high grade PVC by precipitation from solvent
30
Q

polymers as waste fuels

A
  • hard to recycle as high stored energy value
  • incinerated to produce heat - steam for electricity
31
Q

feedstock recycling

A
  • converting polymer chains back to monomers/resembling crude oil
  • used as raw materials to make new polymers
32
Q

bioplastics

A
  • made from plant starch, cellulose, plant oils & proteins
  • renewable & sustainable
  • use protects environment & conserves oil reserves
33
Q

biodegradable polymers

A
  • broken by microorganisms into carbon dioxide, water & biological molecules
  • compostable polymers degrade - leave no visible/toxic residue - based on poly(lactic) acid
  • often condensation polymers
34
Q

photodegradable polymers

A
  • has bonds that are weakened by absorbing light to start degradation
  • or light absorbing additives are used

A-Level Chemistry (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions