Pearson Edexcel IAL Chemistry AS Topic 5: Alkenes Question Bank

Pearson Edexcel IAL Chemistry syllabusChemistry YCH11First assessment 2019

Practise alkene formulae, C=C bonding, E-Z isomerism, addition reactions, mechanisms, polymerisation and polymer waste decisions.

Exam points

interpret alkene structures to count σ and π bonds, formulae and unsaturation
apply E-Z rules using priority groups and restricted rotation about the C=C bond
predict products, reagents and mechanisms for hydrogenation, hydration and halogen addition

[Maximum number: 1]

Which of these is not a way of limiting global problems caused by polymer disposal?

developing biodegradable polymers

exporting polymer waste

removing toxic waste gases produced by the incineration of polymers

reusing products made from polymers

(a)

What is the name of compound L ?

Z-oct-3-en-3-ol

E-oct-3-en-3-ol

Z-oct-5-en-3-ol

E-oct-5-en-3-ol

[ 1 ]

(b)

Compound L can also be converted into compound N .

Which reagent should be used?

$\mathrm{Cl}_{2}(\mathrm{~g})$

HCl(g)

$\mathrm{PCl}_{5}(\mathrm{~s})$

KCl(aq)

[ 1 ]

[Maximum number: 2]

Geometric isomerism is shown by 2-chlorobut-2-ene.

(a)

What is the skeletal formula of E-2-chlorobut-2-ene?
□ A

□ B

□ C

□ D

[ 1 ]

(b)

What is the total number of sigma bonds in Z-2-chlorobut-2-ene?

[ 1 ]

[Maximum number: 9]

This question is about the reactions of propene.

(a)

State one similarity and one difference that would be seen when propene is mixed with separate samples of acidified potassium manganate(VII) solution and of bromine water.

[ 2 ]

(b)

Propene reacts by addition polymerisation to form poly(propene).

Draw the structure of poly(propene), showing two repeat units.

[ 1 ]

(c)

Propene reacts with bromine monochloride, BrCl , to form 1-bromo-2-chloropropane as the major product.

[ 3 ]

(i)

Draw the mechanism for the formation of 1-bromo-2-chloropropane in this reaction.
Include curly arrows, and relevant lone pairs.

[ 3 ]

(d)

Propene reacts with steam in the presence of an acid catalyst to form a mixture of the alcohols propan-1-ol and propan-2-ol.

Complete the mechanism for the formation of propan-2-ol, by adding curly arrows.
Include the species formed in the final step.

[ 3 ]

[Maximum number: 9]

This question is about polymers.

(a)

Plastic bags can be made from poly(lactic acid) (PLA), which is biodegradable. Lactic acid is obtained from corn.
An equation for the polymerisation of lactic acid is shown.

[ 6 ]

(i)

Write a balanced equation for the polymerisation of propene using displayed formulae.

[ 2 ]

(ii)

State the meaning of the term biodegradable.

[ 1 ]

(iii)

Give three advantages of biodegradable polymers.
(3)

[ 3 ]

(b)

Isoprene is used to make synthetic rubber. The skeletal formula for isoprene is shown.

[ 3 ]

(i)

State why isoprene does not have geometric isomers.

[ 1 ]

(ii)

A related molecule does show geometric isomerism.

Draw the geometric isomer of this molecule.

[ 1 ]

(iii)

Give a reason why a double bond may result in geometric isomerism.
(1)

[ 1 ]

[Maximum number: 7]

This question is about ethene, $\mathrm{C}_{2} \mathrm{H}_{4}$ .

(a)

Ethene and chlorine react to form 1,2-dichloroethane.

[ 4 ]

(i)

Draw the mechanism for the reaction between ethene and chlorine to form 1,2-dichloroethane.
Include curly arrows, and relevant lone pairs and dipoles.

[ 4 ]

(b)

Ethene reacts with oxygen, $\mathrm{O}_{2}$ , in the presence of a silver catalyst, to form compound Y as the only product.

[ 1 ]

(i)

Compound Y reacts with water to form compound Z. Compound Z is also produced in the reaction between ethene and acidified potassium manganate(VII).

Give the displayed formula of compound Z.

[ 1 ]

(c)

Two reactions of cyclohexene are shown.

[ 2 ]

(i)

Give the reagents and conditions needed for Reaction 2.

[ 2 ]

[Maximum number: 7]

This question is about the production of squalane, a liquid alkane which occurs naturally in human skin and is used in cosmetics.

squalane

(a)

Squalane can be produced from squalene, an alkene present in shark liver oil, by reaction with hydrogen gas in the presence of a suitable catalyst.

[ 2 ]

(i)

Give the name of a suitable catalyst for the hydrogenation of squalene.

[ 1 ]

(ii)

Write the equation, using molecular formulae, for the complete hydrogenation of squalene to squalane.
State symbols are not required.

[ 1 ]

(b)

The E-isomer of beta-farnesene can also be obtained from corn starch.

[ 4 ]

(i)

Explain why beta-farnesene exhibits geometric isomerism and has only two geometric isomers.

You may label the structure and use this in your answer.
(2)

[ 2 ]

(ii)

Draw the skeletal formula of the geometric isomer of E-beta-farnesene, giving a reason why this is named the Z-isomer.

[ 2 ]

(c)

The compound alpha-farnesene, $\mathrm{C}_{15} \mathrm{H}_{24}$ , is a structural isomer of beta-farnesene. The structural formula of alpha-farnesene is

\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}=\mathrm{CH}_{2}

[ 1 ]

(i)

State the number of geometric isomers of alpha-farnesene.

[ 1 ]

Exam points

Question 17

Question 12

Question 12(a)

Question 12(c)

Question 11

Question 11(a)

Question 11(b)

Question 20

Question 20(b)

Question 20(c)

Question 20(d)

Question 20(d)(ii)

Question 20(e)

Question 20

Question 20(a)

Question 20(a)(i)

Question 20(a)(iii)

Question 20(a)(iv)

Question 20(b)

Question 20(b)(i)

Question 20(b)(ii)

Question 20(b)(iii)

Question 21

Question 21(c)

Question 21(c)(i)

Question 21(d)

Question 21(d)(ii)

Question 21(f)

Question 21(f)(ii)

Question 21

Question 21(c)

Question 21(c)(i)

Question 21(c)(iv)

Question 21(e)

Question 21(e)(i)

Question 21(e)(ii)

Question 21(f)

Question 21(f)(ii)