Every Answer in Unit 1

7/27/2019 Every Answer in Unit 1

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1. (a)

+B r2 B r H B r+

ALLOW C 6 H

6 + Br

2 C

6 H

5 Br + HBr

DO NOT ALLOW multiple substitution DO NOT ALLOW Br +

1

(b) (i) White precipitate OR white solid OR white crystals

B r B r

B r

O H

DO NOT ALLOW colourless DO NOT ALLOW white ppt and bubbles DO NOT ALLOW Br

3C

6 H

2OH OR 2,4,6-tribromophenol OR tribromophenol

2

(ii) 1,2-Dibromocyclohexane ALLOW 1,2dibromocyclohexane OR 1-2dibromocyclohexane OR 12dibromocyclohexane OR cyclo-1,2-dibromohexane

DO NOT ALLOW dibromocyclohexane OR C 6 H

10 Br

2 OR

structures1

The Ravensbourne School 1


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(iii) MUST spell delocalised/delocalized or localised/localized correctlyonce in the answer to obtain all 5 marks

benzene electrons or -bonds are delocalised ALLOW diagram to show overlap of all 6 p-orbitals for delocalisation

DO NOT ALLOW benzene has delocalised structure or ring

phenol a lone or non-bonded pair of electrons on the oxygen or the OH group is (partially) delocalised into the ring

ALLOW diagram to show movement of lone pair into ring for phenol

cyclohexene electrons are localised OR delocalised between twocarbons

ALLOW diagram or description of overlap of 2 adjacent p-orbitals for bonding in cyclohexene

DO NOT ALLOW cyclohexene has a C=C double bond IGNORE slip if cyclohexene is written as cyclohexane but -bonding correctly described

benzene has a lower electron density OR phenol has a higher electron density OR cyclohexene has a higher electron density

DO NOT ALLOW charge density OR electronegativity instead of electron density

benzene cannot polarise or induce a dipole in Br 2 OR phenol

can polarise the Br 2 OR cyclohexene can polarise Br

2or the

BrBr bond

ALLOW Br + OR electrophile Br + as alternate to polarise

5 [9]

2.

H C3

N 2H

H C3 N N+

ALLOW ECF on incorrect amine



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ALLOW

H C3

H

N

H

IGNORE Cl ion DO NOT ALLOW if ring is connected to the N triple bond inthe diazonium or if diazonium has a negative charge

ALLOW one mark for correct displayed diazonium if alkyl group is not shown

A L L O W A L L O W

A L L O W A L L O W

f o r b o t h m a r k s f o r o n e m a r k

f o r o n e m a r kf o r o n e m a r k

H C3

H C3H C3

H C3 N N

N N N N+

+

+ N2

HNO2

+ HCl and temp < 10 C OR NaNO2

+ HCl and temp < 10 C

alkaline AND phenol (if temperature stated must be below 10 C) ALLOW NaOH OR KOH & C

6 H

5OH OR phenoxide ion OR

C 6 H

5O

ALLOW reagents and conditions from the equations[5]

3. (a) (i) silver mirror ALLOW Ag(s) OR Ag mirror OR precipitate OR ppt OR solid ALLOW brown OR black OR grey

1

(ii) HOCH2COOH

ALLOW CH 2OHCOOH OR CH

2OHCO

2 H OR HOCH

2CO

2 H

OR displayed OR skeletal formula OR HOCH 2COO

DO NOT ALLOW C 2 H

4O OR 2-hydroxyethanoic acid

1



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(b) HOCH2CHO + 3[O] HOOCCOOH + H

2O

reagents both products ALLOW displayed/skeletal formula/COOHCOOH

if molecular formula used C 2 H

4O

2+ 3[O] C

2 H

2O

4+ H

2O

max = 1

Any correctly balanced equation for partial oxidation can score 1 mark

HOCH 2CHO + [O] HOCH

2COOH

OR

HOCH 2CHO + 2[O] OHCCOOH + H

2O

OR

HOCH 2CHO + [O] OHCCHO + H

2O

OR

HOCH 2CHO + 2[O] HOOCCHO + H

2O

2

(c) (i) HOCH2CH

2OH

ALLOW HO(CH 2 )

2OH OR (CH

2OH)

2OR skeletal formula OR

displayed formula DO NOT ALLOW molecular formula (C

2 H

6 O

2 )

1



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4.

H O

C O O H

ALLOW

H O

C O H2

o r

H OC

O

H O

DO NOT ALLOW incorrect bond linkageC O O H

O H H O

C O O H C O O H

O Ho r o r

[1]

5. (i)

+

C H3C H2 C

HH

H O

H +

1 mark for each curly arrow (1)(1) 2

(ii)

C H3C H2 C

O H

HH (1) 1

(iii) electron pair donor (1) 1



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(iv) electron pair on H attracted to + carbon forming a dative covalent bond (1)the double/ electron pair breaks (1)electron pair now on O (1) 3

[7]

6. (a) (i)

+ +C l2 H C l

C l

(1) 1

(ii) Introduces a permanent dipole on C l 2

/ forms C l +/

Al Cl 3 + C l 2 A l Cl 4

+ C l +

/Al Cl

3+ C l

2 C l + Al Cl

3 (1) 1

(iii)

+ +

C l+

+H

C lC lH

correct dipole / C l + (1)curly arrow from benzene ring to C l + / Cl + (1)intermediate (1)curly arrow from H to regenerate benzene ring in intermediate (1)H+ as other product (1) 4

(iv) electrophilic substitution (1)with electrophilic spelt correctly 1

(b) In benzene, electrons are delocalised/spread out (1)In alkenes, electrons are concentrated between 2 carbons (1)Electrophiles attracted more to greater electron density in alkenes (1) 3

[10]

7. (a) (i) Tollens reagent / ammoniacal silver nitrate (1)

silver mirror / precipitate (1)

butanoate / butanoic acid / unambiguous formula or structure (1) 3



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(ii) Any of:

Br 2

decolourises (electrophilic) addition

Na fizzes redoxSOCl

2/PCl

5/acid chloride white fumes

substitution/chlorination

carboxylic acid + conc H 2SO 4 /acid chloride sweet smell esterification/ condensation

test (1) - observation (1) - type of reaction (1) 3 NOT 2-4DNPH to give no precipitate

(b) recrystallise /purify (the precipitate) (1)

measure melting point (1)

compare with known values (1) 3[9]

8. (a) (i)

N O2 + 6[ H ] + H C l + 2H O2N H3+ C l-

H2O as product (1) balancing (1) 2

(ii) reducing agent (1) 1

(b)

+ N a O H N H2 + H2O + N a C lN H3+ C l-

(or as the ionic equation without Na + or Cl )

C6H

5 NH

2 (1) balanced (1) 2

(c) moles C6H

5 NO

2used = 0.0300 (mol) (1)

theoretical yield of C6H

5 NH

2= 2.79(3) (g) (1) or ecf

actual 72.1% yield = 2.014 (g) / (calculator value 2.013753) (1) or ecf

to three sig figs = 2.01 (g) (1) or ecf 4[9]



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9. Discussion of the -bonding

p-orbitals overlap (1)

above and below the ring (1)

(to form) -bonds / orbitals (1)any of the first three marks are available from a labelled diagrameg

b o n d s

(-bonds / electrons) are delocalised (1)4 marks

Other valid points any two of:

ring is planar /

C-C bonds are equal length / have intermediate length/strength between C=C and C-C /

-bonds are between C-C and/or C-H

bond angles are 120 6 MAX 2 out of 4 marks (1)(1)

Quality of written communicationtwo or more sentences with correct spelling, punctuation and grammar 1

[7]

10. (i) hydrolysis (1)

(sorbitan monolaurate is an) ester (1)

broken down to form an alcohol and carboxylic acid/salt (1) AW/ equation to show the reaction 3

(ii) sorbitan monolaurate is made from a renewable resource/ not based on crude oil (1) AW 1

[4]



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11. (i)

( d o n o t a l lo w a

h a l o g e nc a r r i e r w i t h t h eb r o m i n e )

( d o n o t p e n a l i s e u s eo f a n i t r a t i n g m i x t u r e )

aO H

B

r

B r

B r

O N- +

O H

N O

2

p h e n o l

O H

I I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N a / N a O H I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B 2

. . . . . . . . . . . . H N O3 H N O3

( 1 )

( 1 )( 1 )

( 1 )

3

(ii) dye / colouring / indicator (1) 1

(iii) phenylamine (1) NaNO

2/ HNO

2 (1) + HCl (1)

< 10C (1)add to alkaline phenol (1) 5

[9]

12. bonding in benzeneoverlap of p-orbitals / bonds/electrons (or labelled) (1)

CC C

CC C

H H

H H

HH



11/24

above and below the ring (or shown in a diagram) (1)electrons are delocalised (or labelled) (1)C C bonds are: same length/strength / in between single anddouble / -bonded AW (1)

greater reactivity of phenol(the ring is activated because )lone pair from O is delocalised into the ring (1)so electron density (of the ring) is increased (1)so electrophiles are more attracted (to the ring) / dipole inelectrophile more easily induced (1)( NOT just more easily attacked or susceptible)

Quality of written communication mark for at least twocomplete sentences in which the meaning is clear with correctspelling, punctuation and grammar (1) 8

[8]

13. (a) (i) heat with:

Tollens reagent / ammoniacal silver nitrate (1)

to give: silver mirror / precipitate (1) 2

(ii) aldehydes can be oxidised to a carboxylic acid ora / aldehydes can reduce Ag + to Ag (1) 1

(b) (i) CH3CH=CHCH

2OH (1)

(either stereoisomer) 1

(ii) reduction / redox / addition (1)( NOT hydrogenation) 1

(c) C4H

6O + 5O

2 4CO

2+ 3H

2O (1) 1

[6]



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14. (a)

O +

C C

C l

C l

C l

O

-

H

H

O

OHH

C C

C l

C l

C l

O

O

H

H

H

- OH

C C

H

C l

C l

C l

OH

-

-

curly arrow from O of OH to C (1)

dipole on C=O and curly arrow breaking C=O (1)

structure of the intermediate (1)

curly arrow from O (of the correct intermediate) to H of H

2O (1) (allow O to H + ion here)

curly arrow breaking the HO bond in H2O (1) 5

(b) one mark for the correct answer to each step below with ecf throughoutsteps may come in any order

one weeks supply = 21 dose (1) 5.25 g / 0.0317mol

mass of trichloroethanal = 4.68 g (223mg if done first)0.891 mass of chloral hydrate (1)

60% yield = mass/moles x 100/60 (1) 7.8(0 g) 3

common errors for two marks are: 9.82 g (mass ratio upside down)8.75 g (mass ratio not done)

2.60 g (3 not done), 1.11 g (7 not done), 0.371g (21 not done)7798 g (mg to g not done) etc.

[8]

15. CCl3CH(OH)

2+ [O] CCl

3COOH + H

2O (1) 1

[1]

16. (a)

CO

CC O C C C

HH

H

H H

H

H H

H

H

H

CH

HH

propanoate and ester group (1) 2-methyl propyl (1) 2



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15/24

(c) conditions for nitration of benzene:HNO

3is concentrated (1)

conc H2SO

4is present (1)

heating or stated temp above 50C (1) 3

explanation for greater reactivity of phenollone pair from O atom is delocalised into the ring (1)

greater () electron density around the ring (1)

(the benzene ring in phenol) is activated (1)

attracts electrophiles/ + NO2

more / makes it more

susceptible to electrophiles AW (1) 4

quality of Written Communication mark for at least two legiblesentences with correct spelling, punctuation and grammar 1

[13]

Accept correct skeletal form (even if only for acyl groups) but must have 17C and two double bonds/one triple bond 2

(ii) 6. Ecf from (i). (1) 1[3]

21.O N a +

N O2

( 1 )

O H

N O2

B r B r

O H

N H2

( 1 )

O C O C H

N O2( 1 )

3

O H

N O2

S nc o n cH C l ( a q )N a O H ( a q)

B r ( a q )2 C H C O C l ( l )3( 1 )

4allow bromination in any positions on the ring

[4]



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22. (i)

C

O HH

C

O HH (1) 1

(ii) C 14H10O2 + 4[H] C 14H14O2 (1) 1allow ecf from (i)

[2]

23. delocalised electronselectrons are spread over more than two atoms AW (1)

-bondformed by overlap of p-orbitals/ diagram to show (1) 2

[2]

24. sodium nitrite + HC l / nitrous acid (1)


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25. (a) (i) bromine as an electrophilean electrophile accepts an electron pair (1)

NOT a lone pair

bromine is polarised/has + charge (centre)/dipole on Br-Br/Br +

shown in diagram (1)

appropriate diagram showning a curly arrow from a double/ bond to the Br +/Br + (1)

eg

B r B r B r

+

+

o r

3

(ii) comparison of reactivity of cyclohexene and benzene benzene is (more) stable / more energy required (1)

benzene () electrons are delocalised (1)

benzene has lower electron/- charge density (1)

so bromine is less polarised /attracted to it / benzene is less susceptible to electrophiles (1)

ora for cyclohexene 4

quality of written communication mark for any two of the the terms:

delocalised/localised, -electrons/bonds/system, electron density,dative covalent, activation/stabilisation energy, halogen carrier,heterlytic fission, addition/substitution, polarity used appropriately (1) 1

(b) (i) iodobenzene because

Br is more electronegative than I (1) ora

so the I atom will be positive / + /the electrophile (1) 2

(ii) C6H

6+ IBr C

6H

5I + HBr (1)

or ecf giving C 6H5Br + HI 1[11]



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26. (1) for correct functional group (1) for the rest

H C O C ( C H ) C H2



O

O

O

4 3

2 4 3

2 4 3

C5H

11acceptable 2

[2]

27. (i)

H C C C

O

O

H

H

O

H C C

H H

H

HH

H

(1) 1

(ii) any sensible change in flavour linked to the presence of the ester or loss of the acid (1) e.g.more fruity due to the esterless sour as acids get used up 1

[2]

28. (a) (i) NaOH / Na (1) 1

(ii) C6H

5OH + NaOH C

6H

5O Na + + H

2O /

C6H

5OH + Na C

6H

5O Na + + H

2 (1) 1

(b) (i)

OC

O

-

-

+

(1) 1allow a dipole on just one C=O bond



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(ii)O

-O

CO

(1)(1) 2

(iii) lone/electron pair from oxygen is delocalised into thering /interacts with -electrons (1)

increases -electron density / negative charge(around the ring) (1)

attracts electrophiles more (1) 3

(c) Mr

salicylic acid = 138 (1)

moles (in 1:1 reaction) = 3500 x 10 6/138 = 2.536 x 10 7 (1)

mass of phenol needed = 2.536 10 7 94 = 2384 tonnes (1)

allowing for 45% yield = 2384 100 /45

= 5298/5300 (tonnes) (1) 4

allow 5297.55300allow ecf throughout

[12]

29. (i) nitrous acid / HNO2

1

(ii)

NC H3-N ( C l )

+

(1) 1

(iii) diazonium (ion /salt) (1) 1

(iv) to prevent decomposition / it reacting (diazonium ion) is unstable AW 1

(v) structure showing the amine coupled to the phenol or its salt e.g.

O H

C H3

C H3

NNC H3

N=N (1) rest of structure (joined by two nitrogens) (1) 2[6]



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30. methylation stage (can come anywhere)CH

3Cl / CH

3Br (1)

Al Cl 3

/ FeBr 3

etc. (1)

equation e.g. C6H

6+ CH

3Cl C

6H

5CH

3+ HC l (1)

intermediate name or unambiguous structure (1)

4 marksintermediates and equations will vary if methylation is doneafter nitration or reduction

nitration stage(conc) H

2SO

4 (1)

(conc) HNO3 (1)

equation e.g.: C6H

5CH

3+ HNO

3 C

6H

4(CH

3)NO

2+ H

2O (1)

intermediate name or unambiguous structure (1)4 marks

reduction stagetin/iron (1)HC l (1)equation e.g.: C

6H

4(CH

3)NO

2+ 6[H] C

6H

4(CH

3)NH

2+ 2H

2O

or with H + also on left to give C6H

4(CH

3)NH

3+ (1)

3 marksallow other suitable reducing agents:

Quality of Written Communication mark for a well organisedanswer with the three stages clearly distinguished and sequenced (1)

1 mark 12 [12]

31. (i)O

a correct skeletal aldehyde is shown on C1 (1)rest of the skeletal structure (C

2-C

10)correct (1) 2

(ii) C9H

15CH

2OH + [O] C

9H

15CHO (1) + H

2O (1) 2

NOT COH,allow C

10 H

16 O

[4]

32. (i) flavouring / fruity smell etc 1 NOT perfume or sweetener



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(ii) conc H2SO

4 (1)

reflux/ distil (1) 2

(iii) CH3COOH + C

9H

15CH

2OH CH

3COOCH

2C

9H

15+ H

2O 3

(1) (1) (1)allow C

2 H

4O

2and C

12 H

20O

2

but NOT wrong structuresallow ecf on the wrong acid

[6]

33. (a) any two of fibres / dyes / explosives / pharmaceuticals etc (1)(1) 2

allow any specific examples as long as they do involve aromaticnitro or amine groups eg NOT nylon, fertiliser etc

(b) temp 50-60 (1)concentrated (acids) (1) 2

allow abbreviations for concentrated

(c) C6H

6+ HNO

3 C

6H

5 NO

2+ H

2O

reactants (1) products (1) 2allow a balanced equation for multiple nitration at any

positions

(d) (i) a pair of electrons (1) (electrons) move / transferred /a (covalent) bond breaks/forms (1) 2

(ii) it accepts a pair of electrons (from the benzene) (1) 1 NOT a lone pair

(iii) H( +) (on the ring) is replaced by NO2(+) (1) 1

allow substitutes ignore + charges

(iv) it is not used up / reformed at the end AW (1) 1



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(e) -bonding electrons are delocalised (1)

six -electrons in benzene (1)four -electrons in the intermediate (1)

-electrons are not over one carbon atom /over five carbon atoms / p-orbitals in the intermediate (1)

this must be stated in words to compare benzene and theintermediate

-electrons are over the complete ring / all around the ringall six carbon atoms/ p-orbitals overlapping (1)

Quality of written communicationfor at least two sentences/statements with legible text andcorrect spelling, punctuation and grammar (1) 6

[17]

34. (a) 1 st stagearomatic amine / named aromatic amine / structure (1)sodium nitrite / nitrous acid (1)HC l /H

2SO

4(but not conc) /H + (1)

at


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(d)

S O3- +N a

O H

S O3-

N a+

2H N

(1) (1) 2allow 1 mark if they are both correct, but in the wrong boxes

only penalise a slip with SO3 Na + once

[13]

35. (i) H + /acid / named strong acid eg H2SO

4/ HC l 1

(ii)

C

O

O C

H

Hdisplayed ester group (1)rest of the ester (1) 2

[3]

36. (i) aldehyde / C=O / carbonyl (1) 1

(ii) C6H

5CHCHCHO + 2[H] C

6H

5CHCHCH

2OH (1) 1

allow C 9 H

10O

[2]

37. methodsilver nitrate (1)ammonia / ammoniacal (1)warm / heat (1)silver (mirror) / brown ppt forms (1)

explanationsilver ions reduced / Ag + + e Ag (1)aldehyde oxidised to a carboxylic acid (1)correct structure eg C

6H

5CHCHCOO /COOH (1)

quality of written communicationmark for correct spelling, punctuation and grammar in at least two sentences (1) 8

[8]



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Every Answer in Unit 1