Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AQA A Level Chemistry > 3.3 Halogenoalkanes > Flashcards

3.3 Halogenoalkanes Flashcards

(58 cards)

Start Studying
1
Q

What is the termination step in free radical substitution, use methane & chlorine as an example

A

Where two radicals react together

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

Define a free radical

A

Species with an unpaired electron

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

Write an equation for each of the following steps in the mechanism for the reaction of chloromethane with chlorine to form dichloromethane

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

Haloalkanes produced from free radical substitution can react again with another halogen and undergo further substitution. How to prevent further substitution

A

Use excess alkane

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

What are CFCs, state what they cause

A

Haloalkanes that contain both chlorine and fluorine
They cause depletion of ozone layer

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

Write three equations to show how trichlorofluoromethane is involved in damaging the ozone layer

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why does fluoroethane not lead to the depletion of ozone

A

Doesn’t contain a chlorine
C-F bonds are strong and do not break

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

Define a nucleophile

A

An electron-pair donor

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

Draw mechanism for nucleophilic substitution with NH3, CN and OH. Use bromoethane

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

Reagent and conditions for nucleophilic substitution with OH^-

A

Reagent : NaOH or KOH
Conditions : aqueous solvent & warm

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

Reagents and conditions for nucleophilic substitution by CN^-

A

Reagent : KCN
Conditions : aqueous and alcohol

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

Reagent and conditions for nucleophilic substitution by NH3

A

Reagents : Excess NH3
Conditions : Ethanol solvent, heat and pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Reasons for different rates of hydrolysis

A

As bond enthalpy decreases, it is easier to break C - halogen bond
Weaker the bond, the faster the rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Outline mechanism,eliminations for 2-chlorobutane and draw all possible products

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

State use of CFC’S

A

They are used as refrigerators

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

Initiation step for CH3F in free radical substitution

A

F2 -> .2F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

State conditions necessary for free radical substitution

A

UV light
High temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

State why ultraviolet light is needed in free radical substitution, use chlorine as an example

A

Provides enough energy to break covalent bonds in chlorine to form free radicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In ozone depletio, for formation of reactive species, what are you trying to form

A

A chlorine free radical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
A

C-Br bond is weaker than C-Cl bond as C-Cl bond has higher bond enthalpy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain how an atom can act as a catalyst

Study These Flashcards
A

Not being used up in reaction
Being unchanged at the end
Is regenerated

25
Chlorofluorocarbons are banned in many countries because of their effect on the environment. Why can a single radical cause the decomposition of many molecules in the ozone layer
Cl. (Radical) is regenerated and causes a chain reaction in the decomposition of ozone
26
What does the dot represent in a radical atom
An unpaired electron
27
Write an overall equation to represent the decomposition of ozone into oxygen
2O3 -> 3O2
28
State benefit to life on Earth of ozone in the upper atmosphere
Absorbs harmful UV radiation
29
State how a CFC can contribute to global warming
Absorbs infrared radiation as molecule has polar bonds
30
State how CFCs from chlorine atoms in the upper atmosphere
C- Cl bonds break
31
32
Define nucleophile
Electron pair donor
33
CH3CH2Br reacts with NH3 to produce CH3CH2NH2, state why an excess of ammonia is needed in this reaction
To minimise further substitution as ethylamine can react further to form secondary amines
34
Name compound CH3CH2CN
Propanenitrile
35
36
Sign is plus
37
Skip part a)
38
39
40
Only do second part
Lower concentration Lower temperature Use water as an aqueous solvent
41
What type of stereoisomers are E- Z isomers
Geometrical isomers
42
State reagent in elimination and it’s role in the mechanism
Reagent : NaOH / KOH Role : base
43
44
C because it is an alcohol
45
For nucleophilic substitution, state the role of hydroxide ions is in the mechanism
Nucleophile / electron pair donor / lone pair donor
46
Bromethane can undergo nucleophilic substitution, state the characteristic that enables it to undergo this reaction
There is a polar C-Br bind
47
Conditions of elimination
- ethanolic solvent - concentrated hydroxide - high temperature
48
49
50
When making a haloalkane from an alkane how would you reduce the amount of further subsitution occuring
add excess alkane
51
State the reagents and conditions needed to make a haloalkane from an alkene
Reagent: HCl, HBr Condition: Room temperature and shake
52
State the reagents and conditions needed to make an alkene from a haloalkane
Reagent: NaOH/KOH Condition: Ethanolic (reflux)
53
State the reagents and conditions needed to make an alcohol from a alkene in a single step
Reagent: Steam Condition: Concentrated phosphoric acid
54
State the reagents and conditions needed to make a primary amine from a haloalkane in one step
Reagent: NH3 Condition: Excess (ethanol, heat and pressure)
55
State the reagents and conditions needed to make a primary amine from a haloalkane in two steps
*First ** Reagent: KCN Condition: Aqueous and Ethanolic Second Reagent: Hydrogen Condition: Nickel Catalyst
56
Explain why a haloalkane such as chloromethane is attacked by a nucleophile in a nucleophilic substitution reaction
Chlorine is more electronegative than carbon. Carbon is partially positive. Lone pair on nucleophile is attracted to the carbon
57
58
To go from CH2Br to CH2OH, nucleophilic substitution occurs. Explain why halogeonalkane is attacked by nucleophile
* Bromine is more electronegative than carbon * C is partially positive / electron deficient * Lone/electron pair (on the nucleophile) donated to the partially positive carbon

AQA A Level Chemistry (33 decks)

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