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Date	November 2019	Marks available	1	Reference code	19N.2.sl.TZ0.3
Level	SL	Paper	2	Time zone	TZ0
Command term	Formulate and Apply	Question number	3	Adapted from	N/A

Question

The following shows some compounds which can be made from ethene, C₂H₄.

ethene (C₂H₄) → C₂H₅Cl → C₂H₆O → C₂H₄O

State the type of reaction which converts ethene into C₂H₅Cl.

[1]

Write an equation for the reaction of C₂H₅Cl with aqueous sodium hydroxide to produce a C₂H₆O compound, showing structural formulas.

[1]

Write an equation for the complete combustion of the organic product in (b).

[1]

c(i).

Determine the enthalpy of combustion of the organic product in (b), in kJ mol⁻¹, using data from section 11 of the data booklet.

[3]

c(ii).

State the reagents and conditions for the conversion of the compound C₂H₆O, produced in (b), into C₂H₄O.

[2]

d(i).

Explain why the compound C₂H₆O, produced in (b), has a higher boiling point than compound C₂H₄O, produced in d(i).

[2]

d(ii).

Ethene is often polymerized. Draw a section of the resulting polymer, showing two repeating units.

[1]

Markscheme

«electrophilic» addition ✔

NOTE: Do not accept “nucleophilic addition” or “free radical addition”.
Do not accept “halogenation”.

CH₃CH₂Cl (g) + OH⁻ (aq) → CH₃CH₂OH (aq) + Cl⁻ (aq)
OR
CH₃CH₂Cl (g) + NaOH (aq) → CH₃CH₂OH (aq) + NaCl (aq) ✔

C₂H₆O (g) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (g)
OR
CH₃CH₂OH (g) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (g) ✔

c(i).

bonds broken:
5(C–H) + C–C + C–O + O–H + 3(O=O)
OR
5(414«kJ mol⁻¹») + 346«kJ mol⁻¹» + 358«kJ mol⁻¹» + 463«kJ mol⁻¹» + 3(498«kJ mol⁻¹») / 4731 «kJ» ✔

bonds formed:
4(C=O) + 6(O–H)
OR
4(804«kJ mol⁻¹») + 6(463«kJ mol⁻¹») / 5994 «kJ» ✔
«ΔH = bonds broken − bonds formed = 4731 − 5994 =» −1263 «kJ mol⁻¹» ✔

NOTE: Award [3] for correct final answer.

c(ii).

K₂Cr₂O₇/Cr₂O₇²⁻/«potassium» dichromate «(VI)» AND acidified/H⁺
OR
«acidified potassium» manganate(VII) / «H⁺» KMnO₄ / «H⁺» MnO₄⁻ ✔