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Date	May 2018	Marks available	1	Reference code	18M.2.hl.TZ1.3
Level	HL	Paper	2	Time zone	TZ1
Command term	State	Question number	3	Adapted from	N/A

Question

This question is about ethene, C₂H₄, and ethyne, C₂H₂.

Ethyne, like ethene, undergoes hydrogenation to form ethane. State the conditions required.

[2]

a.i.

Outline the formation of polyethene from ethene by drawing three repeating units of the polymer.

[1]

a.ii.

Ethyne reacts with chlorine in a similar way to ethene. Formulate equations for the following reactions.

[2]

Under certain conditions, ethyne can be converted to benzene.

Determine the standard enthalpy change, ΔH^Θ, for the reaction stated, using section 11 of the data booklet.

3C₂H₂(g) → C₆H₆(g)

[2]

c.i.

Determine the standard enthalpy change, ΔH^Θ, for the following similar reaction, using ΔH_f values in section 12 of the data booklet.

3C₂H₂(g) → C₆H₆(l)

[2]

c.ii.

Explain, giving two reasons, the difference in the values for (c)(i) and (ii). If you did not obtain answers, use −475 kJ for (i) and −600 kJ for (ii).

[2]

c.iii.

Calculate the standard entropy change, ΔS^Θ, in J K⁻¹, for the reaction in (ii) using section 12 of the data booklet.

[1]

c.iv.

Determine, showing your working, the spontaneity of the reaction in (ii) at 25 °C.

[3]

c.v.

One possible Lewis structure for benzene is shown.

M18/4/CHEMI/HP2/ENG/TZ1/03.d

State one piece of physical evidence that this structure is incorrect.

[1]

Markscheme

nickel/Ni «catalyst»

high pressure

heat

Accept these other catalysts: Pt, Pd, Ir, Rh, Co, Ti.

Accept “high temperature” or a stated temperature such as “150 °C”.

[2 marks]

a.i.

M18/4/CHEMI/HP2/ENG/TZ1/03.a.ii/M

Ignore square brackets and “n”.

Connecting line at end of carbons must be shown.

[1 mark]

a.ii.

ethyne: C₂H₂ + Cl₂ → CHClCHCl

benzene: C₆H₆ + Cl₂ → C₆H₅Cl + HCl

Accept “C₂H₂Cl₂”.

[2 marks]

ΔH^Θ = bonds broken – bonds formed

«ΔH^Θ = 3(C≡C) – 6(CC)_benzene / 3 $\times$ 839 – 6 $\times$ 507 / 2517 – 3042 =» –525 «kJ»

Award [2] for correct final answer.

Award [1 max] for “+525 «kJ»”.

Award [1 max] for:

«ΔH^Θ = 3(C≡C) – 3(C–C) – 3(C=C) / 3 $\times$ 839 – 3 $\times$ 346 – 3 $\times$ 614 / 2517 – 2880 =» –363 «kJ».

[2 marks]

c.i.

ΔH^Θ = ΣΔH_f (products) – ΣΔH_f (reactants)

«ΔH^Θ = 49 kJ – 3 $\times$ 228 kJ =» –635 «kJ»

Award [2] for correct final answer.

Award [1 max] for “+635 «kJ»”.

[2 marks]

c.ii.

ΔH_f values are specific to the compound

bond enthalpy values are averages «from many different compounds»

condensation from gas to liquid is exothermic

Accept “benzene is in two different states «one liquid the other gas»” for M2.

[2 marks]

c.iii.

«ΔS^Θ = 173 – 3 $\times$ 201 =» –430 «J K^–1»

[1 mark]

c.iv.

T = «25 + 273 =» 298 «K»

ΔG^ϴ «= –635 kJ – 298 K × (–0.430 kJ K^–1)» = –507 kJ

ΔG^ϴ < 0 AND spontaneous

ΔG^ϴ< 0 may be inferred from the calculation.

[3 marks]

c.v.

equal C–C bond «lengths/strengths»

regular hexagon

«all» C–C have bond order of 1.5

«all» C–C intermediate between single and double bonds

Accept “all C–C–C bond angles are equal”.

[1 mark]

Examiners report

[N/A]

a.i.

[N/A]

a.ii.

[N/A]

c.i.

[N/A]

c.ii.

[N/A]

c.iii.

[N/A]

c.iv.

[N/A]

c.v.

[N/A]

Syllabus sections

Core » Topic 10: Organic chemistry » 10.1 Fundamentals of organic chemistry

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17M.2.hl.TZ2.6b:
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17M.3.sl.TZ1.10b.ii:
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18M.2.hl.TZ1.7c.iii:
Deduce the name of the class of compound formed when the product of (c)(i) reacts with butanoic acid.
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18N.2.hl.TZ0.2d:
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Deduce the structural formula of the compound.
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18N.2.sl.TZ0.2a:
Draw the structural formula of propan-2-ol.
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Draw two structural isomers of methyloxirane.
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16N.1.sl.TZ0.24:
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D. I, II and III
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19N.2.sl.TZ0.3d(ii):
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17M.1.hl.TZ2.37:
In which order should the reagents be used to convert benzene into phenylamine (aniline)?
19M.2.hl.TZ1.2c:
Outline one piece of physical evidence for the structure of the benzene ring.
19M.2.sl.TZ1.1b:
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State the name of the functional group which allows the molecule to be responsive to applied electric fields.
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16N.3.sl.TZ0.20a:
Compare and contrast the functional groups present in methadone and diamorphine (heroin), giving their names. Use section 37 of the data booklet.
19M.1.sl.TZ2.24:
Which compound has the lowest boiling point?

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B. CH₃CH₂CH₂CH₂CH₃

C. CH₃CH(CH₃)CH₂CH₃

D. CH₃C(CH₃)₂CH₃
19M.1.hl.TZ2.32:
Which compound has the lowest boiling point?

A. CH₃CH₂CH₂CH₂CH₂CH₃

B. CH₃CH₂CH₂CH₂CH₃

C. CH₃CH(CH₃)CH₂CH₃

D. CH₃C(CH₃)₂CH₃
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Deduce the formula of the biodiesel formed when the vegetable oil shown is reacted with the reagents in (a).
17M.2.hl.TZ2.7c.i:
State the reagents and the name of the mechanism for the nitration of benzene.
17M.1.sl.TZ2.27:
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A. CH₃CH(Cl)CH(CH₃)₂

B. (CH₃)₂CHCH₂Cl

C. (CH₃)₃CCl

D. CH₃CH₂Cl
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17M.1.sl.TZ1.27:
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C. C₃H₇N(CH₃)₂

D. C₆H₅NH₂
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Suggest the structural formula of this compound.
17M.2.hl.TZ1.7c:
State the reagents used to convert benzene to nitrobenzene and the formula of the electrophile formed.
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Draw the structure of the dipeptide Asp–Phe using section 33 of the data booklet.
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19N.2.hl.TZ0.3d(iii):
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17M.2.hl.TZ2.9b.i:
Hydrogenation of propene produces propane. Calculate the standard entropy change, ΔS^θ, for the hydrogenation of propene.
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19N.3.hl.TZ0.24a:
Infrared (IR) spectroscopy is used to identify functional groups in organic compounds.

Deduce the wavenumber, in cm⁻¹, of an absorption peak found in the IR spectrum of testosterone but not in that of cholesterol.
17M.3.hl.TZ2.3c.iii:
Subsequent steps proceed under differing conditions, forming the dendrimer polymer with the following repeating unit.

State the name of one functional group in this repeating unit.
19N.2.hl.TZ0.3d(ii):
Explain why the compound C₃H₈O, produced in (a)(iv), has a higher boiling point than compound C₃H₆O, produced in d(i).
17M.2.sl.TZ1.6b:
State the typical reactions that benzene and cyclohexene undergo with bromine.
17M.1.sl.TZ1.25:
What are the functional groups in the aspirin molecule?

$\begin{gathered} \begin{array}{*{20}{l}} {{\text{I.}}}&{{\text{Ether}}} \\ {{\text{II.}}}&{{\text{Carboxyl}}} \\ {{\text{III.}}}&{{\text{Ester}}} \end{array} \hfill \\ \hfill \\ \end{gathered}$

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
17M.2.sl.TZ1.6a:
Discuss the physical evidence for the structure of benzene.
21M.1.sl.TZ2.25: What is the IUPAC name of the molecule shown? A. 2,4-dimethylhexane B. ...
17M.2.hl.TZ2.7b.i:
Bromine was added to hexane, hex-1-ene and benzene. Identify the compound(s) which will react with bromine in a well-lit laboratory.
18N.1.sl.TZ0.25:
What is the order of increasing boiling point for the isomers of C₅H₁₂?

A. CH₃CH₂CH₂CH₂CH₃ < CH₃CH(CH₃)CH₂CH₃ < CH₃C(CH₃)₃

B. CH₃C(CH₃)₃ < CH₃CH(CH₃)CH₂CH₃ < CH₃CH₂CH₂CH₂CH₃

C. CH₃C(CH₃)₃ < CH₃CH₂CH₂CH₂CH₃ < CH₃CH(CH₃)CH₂CH₃

D. CH₃CH(CH₃)CH₂CH₃ < CH₃C(CH₃)₃ < CH₃CH₂CH₂CH₂CH₃
19M.2.sl.TZ2.1c(ii):
State the name of product B, applying IUPAC rules.
17M.2.sl.TZ1.5a:
Ethane, C₂H₆, reacts with chlorine in sunlight. State the type of this reaction and the name of the mechanism by which it occurs.
20N.1.hl.TZ0.40:
Which compound with the molecular formula $C_{4} H_{8} O$ has this high resolution ${}_{1}H NMR$ ?

From: libretexts.org. Courtesy of Chris Schaller, Professor (Chemistry)
at College of Saint Benedict/Saint John’s University.

A. but-3-en-2-ol, ${CH}_{2} = CHCH (OH) {CH}_{3}$

B. butanal, ${CH}_{3} {CH}_{2} {CH}_{2} CHO$

C. butanone, ${CH}_{3} {COCH}_{2} {CH}_{3}$

D. but-3-en-1-ol, ${CH}_{2} = {CHCH}_{2} {CH}_{2} OH$
17M.2.sl.TZ2.6b:
Bromine was added to hexane, hex-1-ene and benzene. Identify the compound(s) which will react with bromine in a well-lit laboratory.
17M.3.sl.TZ1.10b.i:
Describe the difference in their structures.
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18M.3.sl.TZ2.2a:
Describe two differences, other than the number of atoms, between the models of ethane and ethene constructed from the kit shown.
19N.3.sl.TZ0.15a: State the names of two functional groups present in all three molecules, using section 37 of...
19N.3.sl.TZ0.9b: State one impact on health of the increase in LDL cholesterol concentration in blood.
20N.2.hl.TZ0.2e:
Compound A and B are isomers. Draw two other structural isomers with the formula $C_{3} H_{6} O$ .
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18M.3.sl.TZ2.2b.i:
The above ball and stick model is a substituted pyridine molecule (made of carbon, hydrogen, nitrogen, bromine and chlorine atoms). All atoms are shown and represented according to their relative atomic size.

Label each ball in the diagram, excluding hydrogens, as a carbon, C, nitrogen, N, bromine, Br, or chlorine, Cl.
17M.2.hl.TZ2.2a.v:
Identify one organic functional group that can react with acidified K₂Cr₂O₇(aq).
17M.2.hl.TZ2.7a.ii:
Identify the functional group that shows stretching at 1710 cm^–1 in the infrared spectrum of this compound using section 26 of the data booklet and the ¹H NMR.
17M.2.hl.TZ1.6c.i:
One possible product, X, of the reaction of ethane with chlorine has the following composition by mass:

carbon: 24.27%, hydrogen: 4.08%, chlorine: 71.65%

Determine the empirical formula of the product.
20N.3.sl.TZ0.9b: State a class of organic compounds found in gasoline.
19N.3.hl.TZ0.24b:
Describe a technique for the detection of steroids in blood and urine.
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22M.2.sl.TZ1.3c(i):
State the name of Compound A, applying International Union of Pure and Applied Chemistry (IUPAC) rules.
17M.3.hl.TZ2.20a.iii:
Suggest two absorbances, other than the absorbances due to the ring structure and C–H bonds, that would be present in the infrared (IR) spectrum of aspirin.
17M.2.sl.TZ1.5c.i:
One possible product, X, of the reaction of ethane with chlorine has the following composition by mass:

carbon: 24.27%, hydrogen: 4.08%, chlorine: 71.65%

Determine the empirical formula of the product.
20N.2.sl.TZ0.1d(v):
Ethoxyethane (diethyl ether) can be used as a solvent for this conversion. Draw the structural formula of ethoxyethane
19N.3.hl.TZ0.24c:
Explain how redox chemistry is used to measure the ethanol concentration in a breathalyser.
21M.1.sl.TZ1.25: What is the name of this compound, applying IUPAC rules? A. 4-methylhex-2-ene B. ...
18M.3.sl.TZ2.2b.iii:
Pyridine, like benzene, is an aromatic compound.

Outline what is meant by an aromatic compound.
20N.3.hl.TZ0.11b: State a class of organic compounds found in gasoline.
20N.3.hl.TZ0.11e(iii):
Suggest a wavenumber absorbed by methane gas.
21M.2.hl.TZ1.5a(ii): State the molecular formula of the next member of the homologous series to which ethene belongs.
21M.2.hl.TZ1.5a(i): State the class of compound to which ethene belongs.
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21M.1.sl.TZ2.28:
Which spectra would show the difference between propan-2-ol, CH₃CH(OH)CH₃, and propanal, CH₃CH₂CHO?

I. mass
II. infrared
III. ¹H NMR

A. I and II only

B. I and III only

C. II and III only

D. I, II and III
18M.2.sl.TZ2.7a:
The Kekulé structure of benzene suggests it should readily undergo addition reactions.

Discuss two pieces of evidence, one physical and one chemical, which suggest this is not the structure of benzene.
21M.2.sl.TZ1.5a(i): State the class of compound to which ethene belongs.
21M.2.sl.TZ1.5a(ii): State the molecular formula of the next member of the homologous series to which ethene belongs.
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21M.2.sl.TZ2.4c:
Write the equation and name the organic product when ethanol reacts with methanoic acid.
20N.2.sl.TZ0.2c:
Compound A and B are isomers. Draw two other structural isomers with the formula $C_{3} H_{6} O$ .
17M.2.sl.TZ2.6a:
Using relevant equations, show the initiation and the propagation steps for this reaction.
20N.2.hl.TZ0.1d(iv):
Ethoxyethane (diethyl ether) can be used as a solvent for this conversion.
Draw the structural formula of ethoxyethane
20N.2.hl.TZ0.2d:
The IR spectrum of one of the compounds is shown:

COBLENTZ SOCIETY. Collection © 2018 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Deduce, giving a reason, the compound producing this spectrum.
19M.2.hl.TZ1.1b:
Draw the structure of one other isomer of xylene which retains the benzene ring.
20N.2.hl.TZ0.4c: Discuss, referring to intermolecular forces present, the relative volatility of propanone and...
20N.2.sl.TZ0.2b:
The IR spectrum of one of the compounds is shown:

COBLENTZ SOCIETY. Collection © 2018 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Deduce, giving a reason, the compound producing this spectrum.
20N.3.sl.TZ0.9f(iii):
Suggest a wavenumber absorbed by methane gas.
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22M.2.hl.TZ2.8d(iv):
Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).
22M.2.hl.TZ2.8e(ii):
Deduce the splitting pattern in the ¹H NMR spectrum for 1-bromopropane.
19M.2.hl.TZ2.1c(ii):
Determine the enthalpy change for the reaction, in kJ, to produce A using section 11 of the data booklet.
22M.2.sl.TZ2.4b: State two features showing that propane and butane are members of the same homologous series.
22M.2.sl.TZ2.4d(i): Draw the full structural formula of but-2-ene.
22M.2.sl.TZ2.4d(iv):
Suggest two differences in the ¹H NMR of but-2-ene and the organic product from (d)(ii).
17M.2.hl.TZ1.6c.ii:
The mass and ¹H NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.
18M.2.sl.TZ1.3c:
One possible Lewis structure for benzene is shown.

State one piece of physical evidence that this structure is incorrect.
17M.2.sl.TZ1.5c.ii:
The mass and ¹H $\,$ NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.
21M.1.sl.TZ1.24: Which series is in order of increasing boiling point? A. CH2CH2CH3OH CH3COCH3 ...
22M.1.sl.TZ2.26:
Which is a homologous series?

A. C₂H₄, C₃H₅, C₄H₆

B. C₂H₂, C₃H₄, C₄H₆

C. C₂H₂, C₂H₄, C₂H₆

D. C₂H₂, C₄H₄, C₆H₆
21N.1.sl.TZ0.25: What is the name of this substance using IUPAC rules? A. 2-ethyl-1-methylbutan-1-ol B. ...

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