Brainscape's Knowledge GenomeTM

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


See full index

Chemistry > 17.6 > Flashcards

17.6 Flashcards

1
Q

how can bromoethane be converted to ethyl propanoate give conditions reagents and the types of reactions

A

bromoethane -> ethanol
reflux with aqueous potassium hydroxide
hydrolysis reaction
ethanol -> ethyl propanoate
heat with propanoic acid using an acid catalyst
esterification reaction

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

give 4 ways you can extent the length of a carbon chain

A
  • react a halogenoalkane with cyanide ion to form a nitrile
  • addition of hydrogen cyanide to a carbonyl compound
  • alkylation of benzene
  • grinard reagents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are Grignard reagents

A

organometallic compounds containing magnesium

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

how are Grignard reagents formed

A

halogenoalkane/haloarene heated under reflux with magnesium and a solvent of dry ether

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

what is the general equation for the formation of a Grignard reagent

A

R-Br + Mg -> R-Mg-Br

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

what is formed and what is the equation for the reaction of a Grignard reagent with carbon dioxide

A

carboxylic acid
RMgBr -> RCOOH

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

what is formed and what is the equation for the reaction of a Grignard reagent with methanal

A

primary alcohol
RMgBr -> RCH2OH

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

what is formed and what is the equation for the reaction of a Grignard reagent with an aldehyde (R’CHO)

A

secondary alcohol
RMgBr -> RR’CHOH

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

what is formed and what is the equation for the reaction of a Grignard reagent with a ketone (R’COR’’)

A

tertiary alcohol
RR’R’‘COH

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

when can Grignard reagent reactions be used to increase straight chain length

A

reaction with carbon dioxide and methanal

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

when can Grignard reagents be used to create branched molecules

A

reaction with aldehydes and ketones

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

define hazard

A

property of a substance that could cause harm to a user

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

what is a risk

A

the possible effect that a substance may cause to a user, this will depend on factors such as concentration and apparatus

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

what are mercury thermometers often replaced by to reduce risk

A

digital thermometer

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

how can you reduce risk of using a Bunsen burner

A

use a heating mantle instead

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

how can you reduce risk when heating volatile organic compounds

A

heat under reflux to stop the reaction mixture escaping from the reaction with a reflux condenser

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

where does the water enter and leave a reflux condenser

A

enters at the bottom near the reaction mixture and leaves at the top

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

how can you separate an impure liquid using simple distillation

A

heat it in a flask connected to a condenser and the liquid with the lowest boiling temperature will pass into the condenser first and is collected in the receiver separately from the rest of the mixture

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

why is the thermometer important in simple distillation

A

because it monitors the temperature of the vapour, if temp remains steady it indicates 1 compound is being distilled off and when the temperature begins to rise another compound will be beginning to be distilled

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

what are the advantages and disadvantages of using simple distillation

A

+/ easier to set up
faster
-/ does not separate liquid as well as fractional distillation
can only be used if the bp of the liquids is significantly different (<25)

21
Q

what does steam distillation do

A

separates insoluble liquid from an aqueous solution

22
Q

how is steam distillation carried out

A
  • pass steam into a reaction mixture that contains an aqueous solution and a separate liquid layer
  • the top liquid evaporates and is collected in the receiver
23
Q

what are the advantage of steam distillation

A

insoluble liquid is removed from the reaction mixture below its normal boiling temperature

24
Q

what is the advantage of using steam distillation with phenylamine

A

the temperature at which the phenylamine distils is much lower than its boiling temperature so there is less chance of decomposition

25
Q

why has the fractioning column got glass beads in it

A

act as a surface on which the vapour leaving the column can condense and evaporate again so that repeated distillation occurs as it passes up the column which provides better separation

26
Q

what does immiscible mean

A

doesn’t form a mixture

27
Q

what must the properties of the solvent be for solvent extraction

A

should be immiscible with the original solvent
desired product must be more soluble in it than the original solvent

28
Q

describe solvent extraction

A
  • place reaction mixture in a separating funnel than add chosen solvent in small proportions as this is more effective
  • agitate mixture by inverting funnel multiple times
  • allow contents to separate into 2 layers
  • remove stopper and open tap to allow lower layer to drain out
  • then drain the top layer into a separate flask
29
Q

what is always the next step after solvent extraction

A

simple or fractional distillation

30
Q

how can washing be used to get a pure solid

A

stir impure solid with solvent which dissolves impurities but as little substance as possible then filter out the now pure solid

31
Q

how can washing be used to get a pure liquid

A

mix the mixture with a solvent which dissolves the impurities but not the substance then separate with solvent extraction (separating funnel)

32
Q

state some common drying agents

A

calcium chloride
magnesium sulfate
sodium sulfate

33
Q

how do drying agents work

A

the anhydrous metal salts form hydrated salts when they come into contact with water so absorb water as water of crystallization

34
Q

what is observed when a drying agent is used

A

begins powdery than goes more crystalline

35
Q

how do you know the organic liquid is dry when using drying agents

A

if more drying agent is added and remains powdery it indicated that the liquid is dry

36
Q

what is the main piece of apparatus needed for filtration

A

Buchner funnel

37
Q

summarise the steps in recrystallisation

A
  • add impure solid to conical flask
  • add chose solvent and warm to near boil
  • continue this until the solute has fully dissolved
  • if insoluble impurities are left then these must be filtered out
  • allow liquid to cool until crystals have formed
  • dry further with Buchner funnel
38
Q

how can you check a compound is pure

A

if solid - measure melting temperature
if liquid - measure boiling temperature

39
Q

why is chromatography used

A

to separate a mixture into its individual components
to identify the components of a mixture

40
Q

why must a lid be placed on the container for paper chromatography

A

to prevent evaporation of the solvent

41
Q

what is the stationary phase in paper chromatography

A

the liquid or solid that does not move

42
Q

what is the mobile phase in paper chromatography

A

the liquid that moves through the stationary phase and transports the components

43
Q

if a component moves far up the paper what is its attraction to the mobile and stationary phase

A

strongly attracted to the mobile phase
weakly attracted to the stationary phase

44
Q

if a component does not move far up the paper what is its attraction to the stationary and mobile phase

A

strongly attracted to the stationary phase
weakly attracted to the mobile phase

44
Q

what is the stationary and mobile phase of paper chromatography

A

stationary - water trapped in the fibers of the chromatography paper
mobile - solvent

45
Q

what is the equation for Rf value

A

distance travelled by solute/distance travelled by solvent

46
Q

what does Rf stand for

A

retention factor

47
Q

whats the difference between paper chromatography and thin layer chromatography

A

TLC uses a sheet of plastic or glass coated in silica or alumina instead of paper

48
Q

what is the advantage of using column chromatography

A

larger quantities of material can be separated

Chemistry (46 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions