Brainscape's Knowledge GenomeTM

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


See full index

Biosciences > Chem 2b > Flashcards

Chem 2b Flashcards

1
Q

Test for Halide ions

A

Silver nitrate solution followed by ammonia solution.

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

Uses of esters

A

Solvent
Plasticiser
Food flavouring

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

What reactions is NaOH used for?

A

Saponification of triglyerides/hydrolysis of esters

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

What reaction is K2C2O4 used in?

A

Oxidation of alcohols

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

What reaction is NaBH4 used in?

A

Reduction of ketones, aldehydes and carboxylic acids.

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

What reaction does conc. H2SO4 catalyse?

A

Esterification of water and carboxylic acid

Nitration of benzene

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

Nucleophiles which attack acyl chlorides?

A

Alcohol
Primary amine
Water
AMmonia

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

Nucleophillic addition elimination of acyl chloride by primary amine forms?

A

N-substituted amide

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

Nucleophillic addition elimination of acyl chloride by water forms?

A

Carboxylic acid

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

Nucleophillic addition elimination of acyl chloride by ammonia forms?

A

Amide

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

Nucleophillic addition elimination of acyl chloride by alcohol forms?

A

Ester

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

Why is formation of esters by acylation favourable?

A

Goes to completion; it is not an equilibrium

Does not need conc. sulphuric acid catalyst.

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

Why is ethanoic anhydride preferred to enthanoyl chloride for industrial level acylation?

A

Cheaper
Less corrosive
Less vulnerable to hydrolysis (reaction with water)
Safer.

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

What are nitration reactions used to make?

A

Explosives

Dyestuff

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

Why does atomic radius increase going down group VII?

A
  • Number of electron shells increase
  • Shielding increases
  • Outer electrons are further from the nucleus
  • Outer electrons are less strongly attracted.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why does electronegativity decrease going down group VII?

A
  • Number of electron shells increase
  • Shielding increases
  • Electrons in covalent bond are further from nucleus
  • Electrons in covalent bond are less strongly attracted.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does boiling point increase going down group VII?

A
  • Atomic radius increases
  • Size of molecules increases
  • Surface area increases
  • Strength of van der Waal’s forces increases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why does oxidising power of halogens decrease going down the group?

A
  • Number of electron shells increase
  • Shielding increases
  • Ability to attract electrons from other atoms decreases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Trend in oxidising power going down group VII?

A

Decreases going down

A more powerfully oxidising halogen displaces a less powerful one from a solution of halide

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

Why does reducing power of halides increase going down the group?

A
  • Number of electron shells increase
  • Shielding increases
  • Outer electrons are further from nucleus, less strongly attracted so lost more easily.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Test for halide ions

A

Silver nitrate solution followed by ammonia solution

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

Conditions for nitration of benzene

A

Benzene reacted with conc. HNO3 in the presence of conc H2SO4 at 50°C.

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

Initial reaction between reactant and catalyst in nitration of benzene

A

HNO3 + H2SO4 ⇋ NO2+ + HSO4– + H2O

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

What are nitration reactions used to make?

A

Explosives

Dyestuffs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Alkylation

A

Placing an alkyl group onto the benzene ring

26
Q

Conditions for friedel crafts acylation

A

Completely dry, warm

AlCl3 catalyst was present

27
Q

Initial reaction in friedel crafts acylation between reagent and catalyst

A

CH3Cl + AlCl3 —> +CH3 + AlCl4-

28
Q

Relative strengths of amines in comparison to ammonia.

A

aliphatic amines are stronger bases than ammonia.

aromatic amines less strong bases than ammonia.

29
Q

Preparation methods of amines

A
  • Nucleophillic substitution of haloalkanes
  • Reduction of nitriles.
  • Reduction of nitrobenzene to form phenylamine
30
Q

Poisonous sulfur gas with an unpleasant smell

A

H2S

31
Q

State what is observed when concentrated ammonia solution is added to AgI.

A

No visible change

32
Q

State why the silver nitrate is acidified when testing for iodide ions.

A

To remove carbonates and hydroxides that would form precipitates

33
Q

Reaction between KCl and H2SO4

A

2KCl + H2SO4 → K2SO4 + 2HCl

34
Q

Observations of the reaction of KBr(s) w/ conc. H2SO4

A

Brown choking gas

Misty fumes

35
Q

Equation for redox reaction that occurs when KBr reacts with conc. H2SO4

A

2Br- + H2SO4 + 2H+ → Br2 + SO2 + 2H2O

36
Q

Equation showing formation of SO2 when conc. H2SO4 oxidises halide

A

H2SO4 + 2H+ + 2e- → SO2 + 2H2O

37
Q

All possible sulphur-containing reduction products formedwhen conc. H2SO4 oxidises halides

A

SO2
S
H2S

38
Q

Equation showing formation of S when conc. H2SO4 oxidises halide

A

H2SO4 + 6H+ + 6e- → S + 4H2O

39
Q

Equation showing formation of H2S when conc. H2SO4 oxidises halide

A

H2SO4 + 8H+ + 8e- → H2S + 4H2O

40
Q

Explain why hydrochloric acid should not be used to acidify the silver nitrate.

A

COntains Cl- which would give a white ppt

41
Q

State and explain what would be observed when acidified silver nitrate solution is added to a solution of sodium fluoride.

A

No visible change

AgF is soluble

42
Q

Nucleophile

A

Electron pair donor

43
Q

state and explain the stability of benzene compared with the hypothetical cyclohexatriene

A

Benzene is more stable than cyclohexatriene
Expected ΔHο hydrogenation of C6H6 is 360
Actual ΔHο hydrogenation of benzene is 152
Because of delocalisation of electrons

44
Q

Equation showing the formation of NO2+

A

H2SO4 + HNO3 → HSO4– + NO2+ + H2

45
Q

Conditions required for nucleophillic substitution of chlorocyclichexane by NH3

A

Excess NH3 under pressure in sealed tube

46
Q

Reducing agents for hydrogenation of nitrobenzene

A

H2 or Ni

47
Q

Why is nitrobenzene a worse reducing agent than ammonia

A

Lone pair on nitrogen less available as it is delocalised into benzene ring due to the negative inductive effect

48
Q

Conditions for electrophillic substitution/nitration of benzene by HNO3

A

conc. H2SO4 and HNO3

Warm

49
Q

Obervation when Na2CO3 is added to an acid

A

Gas evolves

50
Q

Obervation when Na2CO3 is added to an ester/aldehyde

A

No visible change

51
Q

How to distinguish between an acyl chloride and chloroethane?

A

Add water
Acyl chloride - Violent reaction/steamy fumes
Chloroethane - no visible change

52
Q

Name (CH3)2NH

A

Dimethyl amide

53
Q

Use of a quarternary ammonium salt

A

Fabric softener

54
Q

Explain why the melting point of aminoethanoic acid is much higher than that of hydroxyethanoic acid, HOCH2COOH

A

aminoethanoic acid contains ionic bnding which is much harder to break than the hydrogen bonding in hydroxyethanoic acid.

55
Q

Racemic mixture

A

Equimolar mixture of the enantiomers

56
Q

State how separate samples of the stereoisomers could be distinguished

A

They rotate the plane of polarised light in opposite directions.

57
Q

By considering the shape of the reactive intermediate involved in the mechanism of this reaction, explain how a racemic mixture of the two stereoisomers of 2-chlorobutane is formed.

A

The carbocation intermediate is planar. It will be attacked equally from above (forming one enantiomer) or below (forming the other).

58
Q

Butylamine can be made in a two-step synthesis from CH3CH2CH2Br. Write an equation for the two steps in this synthesis.

A

CH3CH2CH2Br + CN- → CH3CH2CH2CN + Br-

CH3CH2CH2CN + 2H2 → CH3CH2CH2CH2NH

59
Q

Explain why butylamine is a stronger base than ammonia.

A

R group increases electron density having a positive inductive effect
So lone pair on nitrogen is more available

60
Q

Explain why polyamides can be made into fibres suitable for use in sewing and weaving, whereas polyalkenes usually produce fibres that are too weak for this purpose.

A

Polyamides have H bonding, polyalkenes have van der Waals forces
H bonding is stronger

61
Q

What is the chemical used as a reference in NMR and why?

A

Si(CH3)4
Gives one single intense peak well away from others
Non-toxic, inert, volatile.

Biosciences (24 decks)

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