Bonding in Organic Compounds_Industrial Uses & Applications Marks Scheme.unlocked

8/12/2019 Bonding in Organic Compounds_Industrial Uses & Applications Marks Scheme.unlocked

1/21

1. (i) When calcium oxide and coke are heated in an electric furnace, the products are carbonmonoxide and calcium dicarbide (CaC2). Write the equation for this reaction.

CaO + 3C CaC2+ CO (1)

(ii) Addition of water to calcium dicarbide leads to the formation of calcium hydroxide andethyne (ethyne has the formula C2H2and is the starting point for the manufacture of a

variety of substances, including rayon and PVC). Write the equation for the productionof ethyne.

CaC2+ 2H2O Ca(OH)2/CaO2H2+ C2H2(1)

(iii) Until recently most ethyne was made in industry by the method in (ii). Today, ethyne isproduced in industry by heating methane (CH4) alone at a high temperature for 0.01

second. Write an equation for this reaction.2CH4C2H2+ 3H2(1)

(iv) Draw a diagram showing the electron arrangement in the dicarbide ion C22.

Triple bond with co rrect total number of electrons (2)

(5)

2. (a) Benzene and methylbenzene may be separated by fractional distillation. Sketch thegeneral form of the boiling point/composition diagram for such a mixture and use it to

explain the basis on which fractional distillation rests.

0 1

b.p. of benzene

temperature/C

b.p. of methylbenzene

mole fraction of methylbenzene vapour line (1)

liquid line (1)tie line (1)vapour richer in more volatile component (1)must be a verbal statementrepeat tie lines (1)

dist illate is benzene () and residue is methylbenzene () must be averbal statement

(6)


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(b) (i) All lighter (more volatile) fractions from petroleum distillation are useful as fuels.Suggest two reasons why the liquid fractions with 8 to 12 carbon atoms per

molecule are used as motor fuels, rather than the gaseous ones containing from one

to four carbon atoms.higher Hcper mole / greater amount of energy per mole (1)

greater density or words to that effect / some reference to volume occupied(1)possible hazard o f carrying compressed gases (1)

discussion on the presence of branched chains in liquids (1)(max 2)

(2)

(ii) Benzene is added to unleaded petrol to compensate for the absence of tetraethyl

lead. Both compounds are hazardous; which hazard is associated with benzene,other than its flammability?carcinogenic or words to that effect (1)notjust toxic

(1)

(iii) Suggest two reasons why unleaded fuel has been promoted by government and the

petroleum industry.lead toxic (1)another reason eg effect on childrens intelligence (1)reference to poisoning of catalytic converters (1)(max 2)

(2)(Total 11 marks)

3. (a) All lighter (more volatile) fractions from petroleum distillation are useful as fuels.

Suggest two reasons why the liquid fractions with 8 to 12 carbon atoms per molecule areused as motor fuels, rather than the gaseous ones containing from one to four carbon

atoms.higher Hcper mole / greater amount of energy per mole (1)

greater density or words to that effect / some reference to volume occupied (1)possible hazard o f carrying compressed gases (1)discussion on the presence of branched chains in liquids (1)(max 2)

(2)

(b) Benzene is added to unleaded petrol to compensate for the absence of tetraethyl lead.

Both compounds are hazardous; which hazard is associated with benzene, other than its

flammability?carcinogenic or words to that effect (1)not just toxic

(1)

(c) Tetraethyl lead or benzene are added to petrol to prevent pre-ignition.

What is pre-ignition, and why is it a problem?mixture in cyli nder ignites before piston reaches top of stroke/ beforemaximum compression/before spark (1)not just a restatement of pre-ignitionengine damage or power loss or loss of efficiency (1)not just pinking orknocking unless explanation given

(2)


3/21

(d) Suggest two reasons why unleaded fuel has been promoted by government and thepetroleum industry.

lead toxic (1)another reason eg effect on childrens intelligence (1)reference to poisoning of catalytic converters (1)(max 2)

(2)(Total 7 marks)

4. (a) When excess methane reacts with chlorine, the main product is chloromethane.

(i) Under what conditions does this reaction occur?sunlight / UC (1)

(1)

(ii) Give the mechanism for this reaction.(initiation) CICI CI+ CI(1)

(propagation) CI + HCH3 CIH + CH3(1)

CICI + CH3 CI+ CICH3(1)

(termination) eg CI+ CI CI2(1)

if correct use of half arrow these take place of

does not have to be on the C atom ie CH3is acceptable.

(4)

(b) Heptane and octane are liquids at room temperature with boiling points of 98C and126C respectively.

(i) What type of intermolecular forces of attraction are present in such liquids?van der Waals/dispersion / induced dipole-induced dipole /

instantaneous dipole (1)

(1)

(ii) On the axes below, sketch a graph of how the boiling points of various mixtures ofthese two liquids vary with composition. Show clearly the composition of the

liquid and vapour phases.

0

Temperature

mole fraction of heptane 1

lines correct shape ()and labels ()

there must be 2 curves without a max or min in the diagram

the liquid line must notbe straight

correct orientation according to axes (1)

(2)

(iii) By what process would a mixture containing a mole fraction of 0.5 heptane be


4/21

separated into pure heptane and pure octane?fractional distillation (1)

(1)

(c) Liquid alkanes such as heptane and octane occur in petrol used as fuel to drive cards.

(i) Give two reasons why liquid fuels are generally preferred to gaseous ones.any TWO from:

liquids have smaller volume can carry more fuel OWTTE (1)(ie some reference to volume and consequence)

gases would need high pressures and therefore more likely escape (1)

(ie some reference to pressure and reason)

liquids easier to transfer (1)(max 2)

(2)

(ii) The combustion characteristics of fuels for internal combustion engines in cars canbe considerably improved by adding branched chain alkanes, cycloalkanes,

aromatic hydrocarbons or tetraethyl lead(IV) (lead tetraethyl). Two of these are

now considered to be hazardous to health. Select these two and identify the healthhazard with which each is associated.aromatics () carcinogenic ()

lead compounds () lead poisoning etc ()

hazard is consequential on compound chosen

(2)

(Total 13 marks)

5. Liquid alkanes such as heptane and octane occur in petrol used as fuel to drive cards.

(i) Give two reasons why liquid fuels are generally preferred to gaseous ones.any TWO from:

liquids have smaller volume can carry more fuel OWTTE (1)

(ie some reference to volume and consequence)

gases would need high pressures and therefore more likely escape (1)

(ie some reference to pressure and reason)

liquids easier to transfer (1)(max 2)

(2)

(ii) The combustion characteristics of fuels for internal combustion engines in cars can be

considerably improved by adding branched chain alkanes, cycloalkanes, aromatic

hydrocarbons or tetraethyl lead(IV) (lead tetraethyl). Two of these are now considered to

be hazardous to health. Select these two and identify the health hazard with which eachis associated.

aromatics () carcinogenic ()lead compounds () lead poisoning etc ()

hazard is consequential on compound chosen

(2)

(Total 4 marks)


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6. One use of nitric acid is to make inorganic nitrate fertilisers such as ammonium nitrate. Organiccompounds, e.g. urea, are also used. Discuss the relative merits of these compounds as

nitrogenous fertilisers.TEMPERATURE:

increase t moves equilibrium r ight (1)

H (+) (1)

and increases rate (1)

k.e. of molecules increased / more molecules have EA(1)

PRESSURE:

increase pressure no effect on equilibrium position (1)

same number moles of gas on each side (1)

increases rate (1)

ECONOMICS:

and the following related to the economics of the process:

recognition of need to move equilibrium right (1)

and increase rate (1)

not reference to catalyst

(Total 4 marks)

7. (a) (i) use of mixed acid increases concentration of NO2+/ creates NO2+ (1)

electrophile orsome comment on the way H2SO4does this (1)

OR

full equation (2) 2

(ii) (reaction exothermic and) temperature must not rise (1)some indication that the temperature

must be kept down nottoo exothermic 1

(iii) too much conversion to dinitrobenzene otherwise /to prevent further nitration (1)if this is not mentioned in (iii) but then given in

(iv) the mark can be awarded 1

(iv) optimum rate / good yield (1) 1

(v) acid and benzene immiscible / there are 2 layers / maintain mixing of reactants (1)

so rate slow if not mixed orensure reactants are in contact (1) 2

(vi) removes/dilutes most of the acid remaining (1)

if this is notmentioned in (vi) but then given in(vii) the mark can be awarded 1

(vii) removes residual acid dissolved in nitrobenzene (1) 1

(viii) separates nitrobenzene from other volatile constituents / this is the temperature overwhich pure nitrobenzene will distill (1) 1

(b) tin / tin(II) chloride / Fe (1)

(concentrated) HCl (1)ignore any reference to concentration of HCl this mark isconditional on tin / tin(II) chloride / Fe or Sn2+being given heat (1)this mark isconditional on both reagents being correct not LiAlH4which gives other products 3


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(c) (i)

NH CONHCO

enough to make structure clear

amide links (1)correct 1,3 position of ring (1)some idea of extension required (ie the end groups must notbe terminated)brackets not necessary 2

(ii) polyamide orcondensation (1) 1

(iii) acid chlorides (much) more reactive / more easily reacted (1)

give faster polymerisation / better yield (1) 2

(iv) add SOCl2/ PCl5/ PCl3(1)

COCl

COCl

(1)

2[20]

8. (a) (i) D (1) 1

(ii) ionic (1)hydration energies of ions (OWTTE) / water is polar (1) 2

(b) (i) B (1) 1

(ii) B has longalkyl etc chain i.e. focussing on the C15H31group /

A and C have moresites for H bonding (1) 1

(c) (i) esterification (1) 1

(ii) acid (catalyst) (1)H+acceptable heat under reflux (1)

or

conc (1) sulphuric acid (1) 2

(iii) A to B: C15H31CO2H or the acid chloride (1) notC16H32O2C to D: NaOH / NaHCO3/ Na2CO3(1) 2

(d) (i) dissolve in min ()quantity

hot ()suitable solventfilter when hot () cool ()to crystallise

filter () wash () dry () (3 max 3) 3

(ii) determine melting point and compare to known values (1)

orsharp melting point (1)

if spectroscopy mentioned it must be explained fully 1

(e) hydrolysis (1) not saponification 1[15]


7/21

9. (a) H2SO4 + H2O HSO4 + H3O+(1)

can be expressed inacid 1 base 2 base 1 acid 2 (1) words

need identification of pairs by number or letter, not A B A B alone

sulphuric acid acts as proton donoror water acts as proton acceptor i.e. base(1) 3

(b) (i) both strong acids or both completely dissociated (1) the reaction in both is

H++ OHH2O (1); must have equation for second mark 2

(ii) weak (acid) or incompletely dissociated (1)

needs to ionise during reaction which is an endothermic process or someexplanation of this in candidates own words (1) 2

(c) (i) solution resists change in pH (NOT constant pH ) or candidates own words

expressing same idea (1)

for small addition of acid or base (1) 2

(ii) +H+: SO42+ H+HSO4

+OH : HSO4+ OH SO42+ H2O

acceptbalanced nonionic equations. 2

(d) (i) Used to introduce hydrophilic or ionic or polar(1)sulphonate or sulphonic acid group (1)

or introduces sulphonate group (1) into nonpolar

or hydrophobic molecules (1) 2

(ii) Do not form scum (1)(with hard water) and reason e.g. form soluble calcium

or magnesium salts or reference to soap forming insoluble salts(1) orlessdetergent is needed (1) [Max 2]

references to lather or environment or clothes cleaner do not score[15]

10. (a) (i) Restricted / no rotation about the C=C bond (1)a d

C C

b e

in the case of sorbic acid a = b and d = e ( )1

The four groups do not need to be different 2

(ii) Four (1)two for each double bond (1) 2


8/21

(b) (i) A system that resists changes ofpH (1)

on the addition of small amounts of H+or OH (1) 2

(ii) RCOOH RCOO + H+ (1)

This equation must show

RCOOK RCOO + K+ (1) or high concentration of sorbate ion from thecomplete ionisation of the salt

This equation, if given, must not show

first equilibrium suppressed (1)

When H+added : RCOO + H+ RCOOH (1)

When OHadded : RCOOH + OH RCOO + H2O reducing the effect of

the addition of the OH (1)

Judge quality of language at this point but show it at the end of the question

as a whole (1)4max

+

Q of L

(c) (i)

CH CH CH CH CHCOOH + 2 Br CH CH CH CH CHCOOH

Br Br Br Br ( )1

3 32

product can be shown as CH3(CHBr)4COOH 1

(ii) Molar mass of sorbic acid = (6 12) + 8 + (2 16) = 112 g mol1 (1)

amount of sorbic acid = 7.00/112 = 0.0625 mol (1)

amount of bromine = 0.0625 2 = 0.125 mol (1)

concentration of bromine solution = 0.125/0.125

= 1.00 mol dm3 (1) 4

(d) (i) Aqueous ethanol favours substitution whereas pure ethanolfavours elimination (1) 1

(ii)CH CH CH CH CHCOOH

OH OH OH OH( )1

3

can also show ----COO

This is consequential on (c)(i) 1

(iii) Large number of OH groups on product will hydrogen bond with water so

soluble (1)

Nonpolar chain in bromo compound inhibits solubility/ cannot hydrogen bond

extensively with solvent /only one OH group /intermolecular bonds stronger than

bonds formed with water (1) 2


9/21

(e) (i) Long hydrophobic chain with polar end (1) 1

(ii)

C H COOCH

3 C H COONa + CHOH

C H COOCH + 3NaOH

C H COOCH

17

17

17

17

35

35

35

35

2

2

2

2

2

( )1

( )1

CH OH

CH OH

Any plausible fat will do but it must be an ester of glycerol for full marks. If ester is

not of glycerol but has at least two acid groups max 2

Use of R in place of Cl7H35is acceptable 3

[25]

11. (a) (i) correct structure (1)

If greater than 5 carbon atoms in chain but substituents at

2,2,4-trimethyl- then give (1), otherwise (0) 2

(ii) structural isomers (1) 1

(iii) 2C8H18 + 25O2 16CO2 + 18H2O

products (1)balancing (1) 2

(iv) 2:125 or 1:62.5 (1)(2:25 scores zero)

consequential on equation given in (iii) 1

(b) comment on need for or hazards involved with use of pressurised storage (1)

or

more energy per unit volume or mass (1) 1

(c) (i) lead is poisonous / ruins catalyst in catalytic converters (1) 1

(ii) RON may not be maintained

or

fuel can cause pinking / knocking / pre-ignition (1) 1

(iii) benzene is carcinogenic (1) 1

(d) (i) 4.6/12 = 4.55 9.1/1 = 9.1 36.4/16 = 2.275 (1)4.55/2.275 = 2 9.1/2.275 = 4C2H4O (1) 2

(ii) CH3CHO (1)

Reasoning based on MS (1)and IR (1)

e.g. Molecular ion is Mr= 44 so C2H4O+is molecular ion (1)

IR wave number at 1720 cm1shows C=O group (1) 3[15]

12. Liquefaction or condensation (1)Fractional Distillation (1)Nitrogen boils off first orhow the air is liquefied orthat CO2/ H2O removed first (1)

[3]

13. (a) (i) 2 14 100 /60 (1) = 46.67 / 46.7% (1) 2


10/21

(ii) Low(er) solubility / not easily leached

non-explosive

neutral

less osmotic pressure / less scorching

slow release Any two for 1 mark each2

(b) Condensation polymerisation formed of a multiple unit with elimination of a simplemolecules (1)

Diagram (1)

e.g.

Cl C

C

C

C

Cl

N N

+ H N N H

O H H

H H

O

OO

Or formation of a polyester

Polyamide - polymer containing C NH

O

/ -CONH- / -NHCO-(1)

Quality of language (1) 4

(c) Ammonia is the stronger base because ammonium ion is the weaker acid (1)

or

The weaker the acid, the stronger is its conjugate base (1)Therefore (NH4

+weaker acid / smaller Ka) ammonia is stronger base (1)

or

Ka for NH4+is less than Ka for conjugate acid of urea (1)

therefore the ammonia is the stronger base (1)

ammonia is stronger base alone = (0) 2

(d) (i) Bromine (1)NOT aq

NaOH (1)Order of adding/addition and heat (1) 3

(ii) NH2NH2(1) 1


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(e) (i) Ammonium nitrate is a solid/ not a gas (1) 1

(ii) KP= PNH3. PHNO3(1)

PNH3= 15.7 = 3.96 atm (1)

3.96 atm = 3.96 1/50 moles of ammonia

= 0.079 moles (1)Moles of NH4NO3= 8.00/80 = 0.100 (1)

% dissoc = 0.079/0.1 100 = 79% (1) 5

(iii) Energy level of product higher than energy level of reactant = thermodynamically

stable (1)

Reaction 1 exothermictherefore thermodynamically unstable /

product more thermodynamically stable than reactants (1)Reaction 2 endothermictherefore thermodynamically stable /

products less thermodynamically stable than reactants (1)

High activation energy means kinetically stable (1)Correct statement about either or both being kinetically stable (1) 5

[25]

14. (a) (280/2 =)140 (1)

5510/114(1) = ()48.3(1) 3

(b) Eg. Hydrogen

Less pollution(1)

Greater energy per unit mass(1)

renewable resource (1)

Eg. Octane

Liquid easily transported (1)

More readily available (1)The two reasons must relate to thesame fuel no mark for fuel itself 2

(c) The answer requires a disadvantage for the fuel chosen in part (b)

Hydrogen needs to be made using electricity / idea of storage problems developed (1)

Octane (air) pollutionor non-renewable(1) 1[6]

15. (a) (i) Valid diagram 4 carbons overall C4H10 (2)

(ii) Valid diagram 4 carbons C = C (2) 4

(b) Valid chlorine substituted product for the structure given in (a) HCl (2) 2

(c) Any chlorine addition product for the structure given in (b) Correctly drawn (2) 2


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(d) Bromine solution added to unknown Red/orange colour of bromine

Goes colourless (3) 3

(e) (i) Repeating unit of CH2

No double bonds shown (2)

(ii) Electrophilic addition (1)

(iii) Any valid use e.g. packaging, containers, electrical insulation, piping, guttering.Any other valid use (1) 4

[15]

16. (a) (i) enthalpy change /heat energy released

on complete combustion of 1 mole of substance under standard conditions (3)

(ii) activation energy needed to be present

before reaction can proceed at reasonable rate (2)

(iii) methane plus oxygen at higher level than products activation energy peak shown

. H shown on diagram (consequential on above) (3) 8(b) (i) 2C2H18+ 25O2 16CO2+ 18H2O

1 mark for correct species 1mark for correct balance (2)

(ii) 1 mole of octane needs 12.5 moles of oxygen1 mole of octane needs 12.5 5 moles of air (1)

1 mole of octane needs 12.5 5 24 dm of air = 1500 dm(1) (2)

(iii) 890/16 (1)

= 55.6 kJ (1) (2)

(iv) 890/24

= 37.1 kJ (2)

(v) More energy per unit of volume

Methane difficult to liquefy/containers for compressed gases heavy

Plus 1 mark for clarity of argument and communication of ideas (3) 11

(c) Source of hydrogen Source of heat (energy)to run process (2) 2

[21]


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17. (a) (i) Rate = k[ (CH3)3CBr] (1)

CH C Br CH C CH C OH

CH CH CH

CH CH CH

+:OH

3 3 3

3

3 3 3

3 3

(1) (1)

The hydroxide ion acts as a nucleophile (1)

The rate equation indicates the species involved in the rate determining step (1)Only the halogenoalkane is involved in the rate equation,

the first step is the rate determining step/the production ofthe carbocation (1) Max 6

(ii) Rate of reaction decrease I Br Cl (1)Because the bond strengths for the CHal bond increase in this order (1) 2

(b)

CH CHCH CH2 2 33

3

3

3

C C

C C

CH

CH

CH

CH

H

H

H

H

(3)

C C

Orbital overlap shown as diagram or words equivalent (1)prevents free rotation (1)

The OHis a base /removes H+(1) 6

(c) C

C

C

H H

H

H

COOCH

COOCH

COOCH

+ 3KOH 3C H COO K + CHOH

CH OH

CH OH

2

22

2

35 35

35

35

17 17

17

17

+

(1) (1)

Stoichiometry LHS (1)(No need for charges)Product is a soap (1). 4

[18]

18. (a) (i) 2H2+ O22H2O

formulae(1)balancing(1)

(ii) C2H5OH + 3O22CO2+ 3H2O

formulae(1)balancing(1) 4


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(b) H2gives more heat per gram or more heat per / ethanol gives

less(1)H2cheaper / ethanol more expensive(1)

H2is gas and so difficult to store/transport because it needs to

be under pressure or needs a strong container(1)

Ethanol liquid needs no special storage conditions(1)H2gives only water which is not a pollutant(1)

ethanol gives CO2which is a greenhouse gas / leads to globalwarming(1)

Ethanol can be a renewable resource needs to be qualified

(1)

e.gmade from sugar or made by fermentation

Full marks can only be obtained for an answer that

includes a clear discussion of the advantages and Max

disadvantages of both types of fuels 5[9]

19. (a) Group of compounds with the same general

formula(1)that

differ by CH2-(1)

Same or similar chemicalproperties / same 3

functional group(1)

(b) (i) CH H

C C

H H

3

At least one repeat unit(1)

evidence of extension of chain(1) 2consequential on correct repeat unit

(ii) CH2(1)

empirical formula of propene/ the repeat unit(1)since polymer made by addition reaction / no loss ofsmall molecules(1) 3

(c) Different chain lengths / areas of crystalline and amorphous structure(1) 1

(d) (i) C-F bond strong / high bond enthalpy / bond not 1easily broken / steric hindrance by fluorine around carbon(1)

(ii) Nonstick coatings e.g. in saucepans, in pipes, on skis,stainproofing of fabrics, waterproof clothing.(1) 1

(e) Onlysingle / sigma bonds in ethane(1)

Ethene alsohas bond(1)

bond weaker (and breaks) / electrons in bond 3more accessible(1)[14]

20. (a) Spectra shows three types / environment of hydrogen(1)

Each peak related to type of hydrogen in ethanol(1)

References to mass spec score zero 2


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(b) (i) Conc. sulphuric acid would produce (some) bromine(1)50% acid produces HBr only (1) 2

(ii) Ammonia(1)heat in sealed tube / under pressure(1)

orConcentrated ammonia(1)at room temperature(1) 2

(iii) Acid protonates -NH2(to -NH3+) / -NH2reacts with H

+( not HCl)(1) 2

ionic more soluble(1)

(c) If 3 steps that works

Correct intermediates score2 marks

Any 3 correct reagents score3 1 marks

Any one correct condition scores 1 mark

CH CH OH CH COOH

CH COONH

CH COCl

CH CONH

3 3

3 4

3

3 2

2

(1)

(1) (1)

(2)

(4) (3)

(5)

-Step Reagent Conditions

1 Potassium dichromate +

named mineral acid orpotassium manganate(VII)

with sulphuric acid

Heat under reflux

2 PCl3/ PCl5/ SOCl2 Dry / room

temperature

3 Ammonia Room temperature

4 Ammonia Room temperature

5 Heat

6

If scheme breaks down mark from start to breakdown and from end back

to breakdownand score best of these two marks

names or correct formulae allowed.

Name scores even if formulae then given and wrong

(d) (i)

2

2

2

2

or

O

O

O

O

O

O

C

C

N

N

C

C

(CH )n

(CH )n

(CH )m

(CH )m

C

C

N

N

H

H

H

H(1) 1

(CH2)n or m represents a sensible unit which may be a benzene ring


16/21

(ii) H2N(CH2)nNH2and ClOC(CH2)mCOCl

(1) (1) 2

Consequential on (i)

Allow caprolactan (2 marks)

or cyclic compound

H2N(CH2)n COCl scores 2 marks

(iii) Toxic if burnt/ non-biodegradable(1) 1[18]

21. (a) (i) H FH F

C CC C

H FH F(n) (n)

Min 2 carbon(1)2 3extension shown for both of them(1).

(ii) Mixture of different chain lengths

orAreas of crystalline and amorphous structure(1) 1

(b) C-F bond extremely strong / requires a lot of energy to break(1) so resistant to hydrolysis or some specified chemical attack(1) 2

(c) Strong C-Cl means herbicide is persistent in environment / non-biodegradable / hard to breakdown(1)

useful for herbicidal effect(1)but potentially toxic / harmful(1) 3

[9]

22. (a) (i) C2H6+ Br2 C2H5Br + HBr (1)

C2H4+ Br2 CH2BrCH2BrALLOWC2H4Br2(1) 2

IGNORE STATE SYMBOLS

(ii) (Free) radical / homolytic (1)substitution (1)

Electrophilic (1)addition (1) 4

(b) (i) H H

C( )Cn

H Cl

1

(ii)

oneAny

NOT

bagscarrier/PVC/plastic

flooring

cableselectricaloncoating

bottles

clothing

framesdoororwindow

pipesWater

1


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(iii) Persists in the environment / persisting as litter

ORnon-biodegradable / not broken down by bacteria (1)

because of strong C-Cl bond (1)

OR

combustion / burning (1)

produces toxic gases /acidic gases/HCI (1)NOT chlorine 2

[10]

23. (a)

C C

F F

F F

Allow one carbon atom but not three or more unless two are bracketed together 1

(b) Resistant/ inert/ unreactive to foods/ cleaning materials

high melting/softening point/ nonflammable/ nontoxic/ stable at high

temperatures 1

(c) Persists in the environment / occupies sites for long time / many sites needed

Allow nonbiodegradable 1

(d) must be related to (c)

CF bond strong so difficult to break chemically / biologically

If nonbiodegradable used in (c), must refer to biological breakdown 1[4]

24. (a) (i) nucleophilic substitution (1) 2

aqueous (1)Ignore heat under reflux hereAllow aqueous ethanol

(ii) elimination (1)ethanolic / alcoholic (1)

heat(under reflux) (1)not h.u.r. , not warm 3

(b) (i) nCH2= CHCl ( CH2CHCl)n

ns (1)must balance

structure of product clearly shown with continuation bonds (1) 2

(ii) Electrical insulation / water pipes / guttering / window frames /

flooring/ specified clothing (1)Do not allow buckets, bottles etc 1

(iii) Either

Remain in landfill sites (1)

not biodegradable / strong CCl bond (1)(both are stand-alone marks)or

If incinerated (1)produce toxic fumes (1)(consequential on incineration)

if specified, must be correct eg HCl or dioxins, not chlorine 2


18/21

(c) (i) 61.0/12 15.3/1 23.7/14 i.e. divide by Ar(1)

5.08/1.69 15.3/1.69 1.69/1.69 i.e. divide by 1.69 to give 3:9:1 (1)or

% C,H and N calculated from given formula (1)

which are the same as the data (1) 2

(ii) Ammonia (1)(Not formula)

CH3CHBrCH3+ 2NH3CH3CH(NH2)CH3/C3H9N + NH4Br

Organic species (1)(consequential on reasonably correct reagent)balancing of equation as above (1) 3

(iii)

Br C C C H

H

H

H

H

H

H

All bonds must be shown 1[16]

25. (a) enthalpy/heat (not energy) change for one moleof a compound / substance (1)

to be formed from its elements(1)in standardstates or under standard conditions of 1atm pressure and stated

temperature (298 K). (1) 3

(b) (i) Hc= [(394) + (2 286)] (75)]

= 891 kJ mol1

891 kJ mol1with working (3)

605 kJ mol1with working (2)all other non-typo values (max 1) for 2 286

891 kJ mol1with no working (1) 3

(ii) (negative so) exothermic

(consequential on (i)) 1

(c) C2H5OH + 3O22CO2+ 3H2O

species (1)balancing (1) 2

(d) QWC

Must compare the two fuels for full marks

Only datagenerated advantages and disadvantages to score.

Methane is a gas and ethanol is a liquid plus a valid comment aboutstorage in vehicle, e.g. methane requires heavycontainer to store gasunder pressure / largecontainer required to store gas, whereas easy to

store liquid in fuel tank (1)

Any 2 of

Methane cheaper per kJ of heat released (than ethanol)

Methane cheaper (per tonne than ethanol)

Methane produces more heat per gram (than ethanol)

Cheaper / more heat implies a comparison 3


19/21

(e) C2H5OH + [O] CH3CHO + H2O (1)not CH3COH

C2H5OH + 2[O] CH3COOH + H2O (1) (allow CH3CO2H)

Allow CH3CHO + [O] CH3COOH if CH3CHO is a product in 1stequation 2

(f) conc. H2SO4/Al2O3/ conc or syrupy H3PO4or names (1)

For acids, conditions: heat (if temp stated conc sulphuric 150 C200 C

phosphoric 50 to 100C)For aluminium oxide, conditions: pass vapour over hot Al

2O

3(1) 2

[16]

26. (a) H2/ hydrogenNOT H (1)

Ni / nickel

OR platinum / Pt / palladium / Pd (1)

(Ni) 140 180 C / heat (1) 3

OR (Pt / Pd) room temperature

If no reagent but other parts correct (1)

Incorrect reagent (0)

(b) (i)

1

(ii) electrophile / electrophilicIGNORE any reference to addition 1

(c) potassium manganate(VII) / potassium permanganate / MnO4/

manganate(VII) ionsIGNOREacid or alkali 1ACCEPT name or formula

(d)

Correct structure (1) only one repeat until identified

Continuation (1)

IGNORE ( )n 2

[8]


20/21

27. (a) (i)

Skeleton (1)NOT C3H7NOT just R for side chain unles specify R = CH3CH2CH2Brackets are not essential

Extension (1) conditional on first mark OR C3H7/ R 2

(ii) nitration

ROOR 2RO(1)Propogation (1)

(1) (1)

ROCH(CH2C2H5)CH2+ C2H5CH2CH = CH2

ROCH (CH2C2H5)CH2CH (CH2C2H5)CH2

Second propagation step consequential on first step

ALLOW C3H7OR CH2C2H5(1)ALLOW any representation of the alkene eg RCH = CH2

A correct use of single headed curly arrow 4IGNORE additional incorrect arrows

IGNORE termination steps


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(b) (i)

(1) for both arrows (1) for structure of intermediate

(1) Arrow

Lone pair not essential, but if it is shown the arrow must start from it

ALLOW arrow from negative chargeALLOW arrow to + if written below the C

ALLOW C3H7/ R

If ethene is used MAX 2for curly arrows 3

(ii) Structures of the 2intermediate carbocations / intermediate cation

giving 2-bromopentane is secondary andprimary for 1-bromopentane (1)Secondary cation is more stable than primary CONDITIONAL

on reference to cations (1) 2

(c) (i) Sample in polarimeter / use of crossed polaroids / pass polarised

light through sample (1)

Rotates the plane of (polarisation of plane)-polarised (monochromatic)light (1)

NOT deflectionNOT reflection 2

(ii) intermediate (carbocation) planar (1)

equal (probability of) attack from either side (1)(leads to) racemic/ 50:50 / equimolar mixture (1) stand alone 3

[16]

Bonding in Organic Compounds_Industrial Uses & Applications Marks Scheme.unlocked

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