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AQA A-Level Chemistry > Paper 2 Misconceptions > Flashcards

Paper 2 Misconceptions Flashcards

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1
Q

Why is TMS used as a reference standard for chemical shifts?

A

Generates one sharp peak always found on far right of spectrum.
Highly volatile and unreactive

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2
Q

What does number of peaks tell you on C13 NMR and H1 NMR?

A

Number of environments

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3
Q

What does the location of the peaks tell you in C13 NMR and H1 NMR?

A

Type of proton environment

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4
Q

What does the integration value/area under each peak tell you for H1 NMR?

A

Number of H+ in the environment

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5
Q

What does the splitting tell you in H1 NMR?

A

Number of H+ in adjacent environments

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6
Q

Singlet

A

No H next to it

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7
Q

What solvent do we use when testing NMR of hydrogen based substances?

A

D2O
CCl4

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8
Q

Problems with nucleophilic subs with excess NH3 to produce primary amine

A

Further substitution to produce a secondary tertiary or quaternary amine

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9
Q

Problems with nucleophilic subs with KCN and reduction to produce primary amine

A

KCN is toxic, lower percentage yield and is 2 steps

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10
Q

Uses of quaternary ammonium salts

A

Hair conditioner

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11
Q

Longer the carboxylic acid chain is the..

A

less soluble it is- hydrocarbon chain is longer and insoluble

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12
Q

Uses of esters

A

Plasticisers
Perfumes
Flavourings

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13
Q

Ester formation reaction conditions and reagent

A

H2SO4 catalyst
Water byproduct
Warm and reflux

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14
Q

Acid catalysed hydrolysis of ester

A

Carboxylic acid and alcohol

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15
Q

Base catalysed hydrolysis of ester

A

Salt of carboxylic acid and alcohol

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16
Q

Use of carboxylic acid salt formed from base hydrolysis of triester

A

Soap

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17
Q

Use of biodiesel

A

Conserve crude oil supplies
Reduce amount of CO2 released

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18
Q

Why are acid anhydrides used more commonly than acyl chlorides

A

Less corrosive
Side product is COOH not HCl

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19
Q

Outline essential features of fractional distillation of crude oil that enables crude oil to be separated

A

Compounds have diff BPS
BP depends on length of compound
Hotter at bottom of column
Heavier molecules condense and collect at bottom

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20
Q

Reaction mixture still reacting in continuous monitoring method. How do we solve this?

A

To stop reaction, QUENCH.
Add large volume of cold, distilled water to both cool and dilute the reaction, reducing the rate.

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21
Q

The volume of gas produced from a reaction could be measured at regular intervals. What is the problem with this?

A

Records amount of product produced when this order of reaction is about reactants, so the volume would need recording into reactant conc.

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22
Q

Continuous monitoring graph labels and how to measure progress of reaction

A

Conc v time
- Take samples at regular intervals
- Use visible indicator such as gas volume

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23
Q

Initial rates graph labels and key points

A

Rate v conc
Volume ∝ Conc
When total volume is constant, the volume of reactant is proportional to its conc

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24
Q

Properties of ordinary PVC vs plasticiser PVC

A

PVC is made of long, closely packed together polymer chains- hard and brittle. Used in drain pipes.

Plasticiser PVC is more flexible- used for electrical cable insulation and clothing

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25
Q

Mechanical recycling

A

Plastics sorted into different types and washed
Ground into pellets
Pellets melted down and remoulded into new objects

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26
Q

Feedstock recycling

A

Plastics sorted into different types
Heated to temp which breaks their polymer bonds
Repolymerised to form new plastics

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27
Q

Addition polymer

A

An Addition Polymer is a long chain formed from many monomers and no other product is formed.

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28
Q

Condensation polymer

A

In a condensation reaction, two molecules join to form a larger one, with a small molecule such as H2O or HCl being released

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29
Q

Two types of condensation polymer

A

Polyamide
Polyester

30
Q

Uses of terylene

A

Carpets
Clothing

31
Q

Uses of nylon and properties

A

Used as fibres in clothing
Elastic, strong abrasion resistant

32
Q

Uses of kevlar and properties

A

Used in manufacture of body armour and crash helmets
Strong, light, heat resistant

33
Q

Why are addition polymers not biodegradable?

A

Have non polar C-C bonds that cannot be hydrolysed

34
Q

Why are condensation polymers biodegradable?

A

They can be hydrolysed under acidic or basic conditions
Delta positive C of polar C-O bond can be attacked by nucleophiles

35
Q

Acid hydrolysis of polyamide

A

NH3+ and COOH

36
Q

Base hydrolysis of polyamide

A

COONa and NH2

37
Q

Acid hydrolysis of polyester

A

OH and COOH

38
Q

Base hydrolysis of polyester

A

COONa and OH

39
Q

Acidic conditions for amino acids

A

Protonated so become NH3+ including R group

40
Q

Alkaline conditions for amino acids

A

Deprotonated so COO- including R group

41
Q

What are enzymes described as?

A

Stereospecific

42
Q

How can the amount of further substitution be reduced?

A

Excess of alkane used

43
Q

Properties of CFCs

A

non-toxic
inert gases
volatile

44
Q

Primary alcohol to Aldehyde

A

1 [O]
Distillation

45
Q

Primary alcohol to carboxylic acid

A

2 [O]
Reflux

46
Q

Aldehyde to carboxylic acid

A

1 [O]
Reflux

47
Q

Secondary alcohol to ketone

A

1 [O]
Reflux

48
Q

Advantage of hydration of ethene

A

Large scale continuous production method

49
Q

Disadvantage of hydration of ethene

A

High temp and pressure needed- increases cost

50
Q

Advantage of fermentation

A

Uses renewable resources

51
Q

Disadvantage of fermentation

A

Slow rate of reaction

52
Q

Advantage of biofuels

A

Come from raw renewable materials to conserve crude oil supplies

53
Q

Disadvantage of biofuels

A

Many other carbon costs in their production so they aren’t carbon neutral (CO2 released during transportation and distillation)

54
Q

Use of condenser

A

Water passes around outside tube w distillate to cool it

55
Q

Use of antibumping granules

A

Prevents large bubbles from forming

56
Q

Why is reflux used to oxidise alcohol into carboxylic acid

A

Reflux doesnt allow any reactant vapour to escape

57
Q

OH in alcohols

A

Finger like/Test tube shape

58
Q

OH in acids

A

Mitten shape

59
Q

Where is the fingerprint region?

A

Fingerprint region is the area of the spectrum below 1500cm-1

60
Q

Dynamic equillibrium

A

Forward and backward reaction occur at equal rate
Conc of reactants and products is constant

61
Q

EMP

A

Most likely energy of particles in a sample

62
Q

Emean

A

Mean energy of particles

63
Q

Why does kinetic energy graph start from origin?

A

No particles have no energy

64
Q

Higher temp graph KE

A

Curve shifts right
Peak lower
Area under curve beyond activation energy increases

65
Q

Lower conc graph KE

A

Peak lower
Area under curve smaller

66
Q

Formation of primary amine in 2 steps

A

Nucleo subs Haloalkane to nitrile
Reduction using H2 and Ni catalyst

67
Q

Formation of phenylamine

A

Electrophilic substitution to form nitrobenzene
Reduction using Sn and conc HCl

68
Q

Is secondary or primary carbocation more stable?

A

Secondary

69
Q

Explain why a nucleophile would attack a haloalkane with Br in a nucleophilic substitution reaction

A

Bromine more electronegative than carbon
C is electron deficient
Lone pair on nucleophile donated to electron-deficient carbon

70
Q

Explain the bonding in and the shape of a benzene molecule

A

Stage 1 Bonding
1a) Each C has three (covalent) bonds
1b) Spare electrons (in a p orbital) overlap (to form a pi cloud)
1c) delocalisation
Stage 2 Shape
2a) Planar
2b) Hexagon/6 carbon ring/120o bond angle
2c) C–C bonds equal in length / C–C bond lengths between single and double bond
Stage 3 Stability
3a) Expected Ho hydrogn of cyclohexatriene = –360 kJ mol–1
3b) Ho hydrogn benzene (is less exothermic) by 152 kJ mol–1
3c) Benzene lower in energy than cyclohexatriene / Benzene is more stable

71
Q

Two ways of maximimising yield of propanal by distillation of reaction mixture

A

Cool distillate
Keep temp of reaction mixture below bp of the thing added e.g. propan-1-ol

AQA A-Level Chemistry (19 decks)

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