Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AS levels Resurrection > C Unit 2.6 Halogenoalkanes Revamp > Flashcards

C Unit 2.6 Halogenoalkanes Revamp Flashcards

1
Q

Define halogenoalkane
(3-way)

A
  • Homologous series (Similar to Alkanes/Alkenes)
  • Which 1/more of H atoms replaced
  • by a halogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do we turn a halogenoalkane from saturated to unsaturated compounds?
(+ what it gives us)

A

Undergoing an elimination reaction
+ separating the halogen

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

How are halogenoalkanes able to undergo an elimination reaction?
(2-way)

A
  • Hydrogen halides are acidic
  • Therefore can be removed using an alkali
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is used to have the halogenoalkane to undergo an elimination reaction?

A

NaOH dissolved in Ethanol

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

Draw 1-bromopropane converted into propene and HBr

A

Stage is yours y’all

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

How can halogenoalkanes form more than 1 product when undergoing an elimination reaction?

A

For only unsymmetrical halogenoalkanes

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

Draw 2-bromobutane and the conversion of 2 products?

A

Stage is yours D:

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

Define nucleophile
(3-way)

A
  • Atom/group of atoms
  • That has an electron pair
  • That can be donated to an e- deficient centre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The significance of halogenoalkanes having a permanent dipole?
(3-way)

A
  • e- deficient carbons can undergo
  • nucleophilic attack leading to
  • nucleophilic substitution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

For any mechanism, what are 4 things that are needed?

A
  1. Lone pairs
  2. Dipoles
  3. Charges
  4. Curly arrows
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Draw the mechanism for the nucleophilic substitution of 1-chloropropane by sodium hydroxide

A

All yours.
Also, spectator ion is totally optional but aye, isn’t it nicer to clarify things?

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

What is the rate of nucleophilic substitution factored on?
(2 things)

A
  • Strength of the carbon-halogen (C-X) bond (bond enthalpy)
  • How strongly they attract electrons? (bond polarity)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Relationship between reactivity, strength of bond, and rate?
(3-way)

A
  • More reactive the halogen,
  • Stronger the bond will be,
  • The longer the reaction will take
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Hence, what are the bond strengths of carbon-halogen bonds for the 4 halogens?
(2 points)

A
  • Fluorine strongest (More electronegative)
  • Downwards, iodine the weakest (Least electronegative)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How come the carbon-fluorine bond may get ignored?
(3 points)

A
  • Very strong
  • Greatest polarity
  • May be very unreactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Hence show rates of reaction from slowest to fastest of halogenoalkanes?

A

RCl > RBr > RI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The purpose of hydrolysing halogenoalkanes?
(Adding water)
(2 things… kinda check up but still serves the purpose)

A
  • Produce alcohols ig? (+ hydroxonium ion)
  • And to test if it’s rlly a halogenoalkane???
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is nucleophilic substitution slow for hydrolysis of halogenoalkanes?
(2 things)

A
  • Water not very good nucleophile
  • Lacks full negative charge (in comparison to -OH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Hence, how to speed up nucleophilic substitution for hydrolysis of halogenoalkanes?

A

Use Sodium Hydroxide (NaOH)

20
Q

Then, draw mechanism for the nucleophilic substitution of 1-chloropropane with water

A

Allll yours pal

21
Q

Therefore, the real way to test for halogenoalkanes?
+ brief explanation

A
  • Using silver nitrate (AgNO3)
  • Observing peculiar ppts
22
Q

What would happen if we used just NaOH insteada water against halogenoalkanes?
Hence a counter?

A
  • Interference of results (totally different outcome)
  • Neutralise alkali by addition of nitric acid (NO3)
23
Q

Chloride w/ Ag+ observation?

24
Q

Chloride w/ Ag+ **addition of NH3** observation?

A

Ppt dissolves

25
Q

Bromide w/ Ag+ observation?

26
Q

Bromide w/ Ag+ addition of NH3 observation?
(2-way)

A
  • If NH3 is concentrated
  • Ppt dissolves (…. otherwise….)
27
Q

Iodide w/ Ag+ observation?

A

Yellow ppt

28
Q

Iodide w/ Ag+ addition of NH3 observation?

29
Q

What are CFCs (chlorofluorocarbons)?
(2-way)

A
  • Halogenoalkane molecules where
  • all H atoms replaced with F/C atoms
30
Q

Describe CFCs?
(3 points)

A
  • Non-flammable
  • Not very toxic
  • Large number of uses
31
Q

Say some uses of CFCs?
(At least know one, like ig it’s deep)

A
  • Refrigerants
  • Propellants for aerosols
  • Generating foamed plastics (e.g. expanded polystyrene/polyurethane foam)
  • Solvents for dry cleaning/general degreasing purposes
  • Anaesthetics
32
Q

The big 3 tragedies of CFCs?

A
  • Largely responsible for destroying ozone layer
  • Contributed to global warming (Not stronger than CO2)
  • Indirect cause of skin cancer (Ozone holes)
33
Q

What caused CFCs to destroying ozone layer?
(5-way)

A
  • At high atmosphere
  • Carbon-chlorine bonds break giving
  • Chlorine free radicals
  • Which destroy ozone layer
  • 1 ˙Cl destroying 1000s of ozone molecules
34
Q

What are ozone holes?
(3-way)

A
  • Marked decreases in concentration of
  • ozone in the ozone layer above
  • north and south poles
35
Q

Tragedy of decrease of ozone concentration?
(2-way)

A
  • Medium to high energy UV radiation
  • reached surface of earth
36
Q

What can medium to high energy UV radiation cause?
(Likewise to previous y’alls in terms of acknowledging)

A
  • Sunburn
  • Skin cancers
  • Eye cataracts
  • Decreased immune response
  • Plant damage
  • Polymer decomposition
37
Q

What was the only truest way to stop ozone destruction by CFCs?

A

… Prevent release of substance

38
Q

How come C-Cl bond was the main radical attacker than other bonds (C-F/C-H)
(2-way)

A
  • More difficult to break C-H/C-F
  • Hence C-Cl pronounced the HIGHEST DPS (main radical)
39
Q

Define reflux?
(2-way)

A
  • Heating a reaction mixture to boiling
  • Process of evaporation and condensation
40
Q

How would we prepare alcohols from halogenoalkanes?
(3-way)

A
  • Nucleophilic substitution
  • w/ Aq sodium hydroxide
  • when heated to reflux
41
Q

Quick alternate method insteada reflux?

A

Distillation

42
Q

Explain how the reflux works
(6 step by steps w/ 1 obviously being 2-way)

A
  • Rxn mixture heated
  • Liquids evaporate
  • Vapour rises up through condenser
  • Condenser has cold-water jacket
  • which’ll cool vapour to a liquid
  • Dripping back into rxn mixture
43
Q

Ig then a simple summarisation of reflux then?
(3-way)

A
  • A continuous process of evaporation and
  • condensation taking place
  • without loss of product
44
Q

The least we can do, list the apparatus and chemicals for reflux of halogenoalkanes?
(Maybe know one? Or acknowledge, I’m unsure.. hence major check-up)

A

Apparatus:
- Round-bottom flask
- Reflux condenser
- Heat source (water bath or heating mantle)
- Anti-bumping granules (to prevent violent boiling)
- Clamps and stand

Chemicals:
- Halogenoalkane (e.g., 1-bromobutane)
- Aqueous sodium hydroxide (NaOH)
- Ethanol (as a co-solvent, because NaOH is not very soluble in halogenoalkanes)

45
Q

Almost there

A

Thank the past self future self

AS levels Resurrection (30 decks)

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