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MINISTRY OF EDUCATION, SINGAPORE

in collaboration with

UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE

General Certificate of Education Advanced Level

Higher 2

478368501

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I iui i

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CANDIDATE

NAME

CENTRE

NUMBER

H MISTRY

Paper 2 Structured Questions

Candidates answer on the Question Paper.

Additional Materials: Data Booklet.

READ THESE INSTRUCTIONS FIRST

INDEX

NUMBER

T ll

9647 2

October November

2011

2 hours

Write your Centre number, index number and name on all the work you hand in.

Write in dark blue or black pen on both sides of the paper.

You may use a soft pencil for any diagrams, graphs or rough working.

Do not use staples, paper clips, highlighters, glue or correction fluid.

DO NOT WRITE IN ANY BARCODES.

Answer

al l

questions.

A Data Booklet is provided.

At the end of the examination, fasten all your work securely together.

The number of marks is given In brackets [

1

at the end of each question or part

question.

Fo r

Examiner s

Use

1

-_ ...

_---

,

2

3

4

5

- - -- -

6

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Total

I

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This document consists of 13 printed pages and 3 blank pages.

Sln.o,Drn E m oatl s

on.

,. mentB

,

e

UCLES MOE 2011 DC LEO 669f7

L

8:

UNIVERSITY

CAMBRIDGE

,

International Examinations

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II

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2

Planning (P)

Aspirin was one of the first drugs to be produced synthetical ly and is one of the most widely

used 'over-the-counter' drugs in the world. It is a white solid and is prepared by an acylation

reaction between 2-hydroxybenzenecarboxylic acid and ethanoic anhydride.

The other product of this reaction is ethanoic acid.

r

x JrJner

s

2-hydroxybenzenecarboxylic acid ethanoic anhydride

aspirin

2-Hydroxybenzenecarboxylic acid is a white crystalline solid.

Ethanoic anhydride is a corrosive llquid which has a density of 1.08gcm-3.

Pure aspirin has a melting point of 135C.

Like most organic reactions, the yield of this reaction is less than 100 . Using the procedure

described below, a typical yield of pure aspirin is 75 .

Equimolar amounts of 2-hydroxybenzenecarboxylic acid and ethanoic anhydride are used,

together with about

8 1

drops of 85 phosphoric acid which catalyses the reaction. When

mixing the reactants, the initial reaction may be violent.

The reaction mixture is then heated under reflux conditions for around fifteen minutes.

About 23cm

3

of water is then added to the hot reaction mixture to hydrolyse any unreacted

ethanoic anhydride. The addition of this water may cause the mixture to boil.

Once the reaction has subsided, the reaction mixture is poured into about

5 cm

3

of

cold water. This causes the aspirin to precipitate. The crude aspirin product is purified by

recrystallisation from water.

(a) Using the information given above:

(I) write a balanced equation for the formation of aspirin;

ii) calculate the masses of reactants you would use to prepare

1 g

of pure aspirin,

showing your working.

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b Write a plan for the preparation of 1Og of pure aspirin

In your plan you should:

draw a diagram of the assembled apparatus you would usa when heating the

reaction mixture;

give a full description of the procedures you would use to prepare and purify the

aspirin ;

explain how you would check the purity of your sample

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[8]

c) Identity one potential safety hazard in this experiment and state how you would

minimise this risk

[1

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2

Phosphorus(V) chloride,

PCls

is a white solid which sublimes at 160 C.

When gaseous phosphorus(V) chloride is heated in a closed container, the following

equilibrium is established.

(a) Write an expression for for this equilibrium, stating the units .

[2]

Phosphorus(V) chloride dissolves in some polar solvents without reaction and such solutions

conduct electricity. This is due to the presence of the two ions [PClJ and [P IJ

(b) Draw the structure and suggest the shape of each of these ions.

[3]

(Total: 5]

or

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3 This question refers to the equilibrium in question 2.

In an experiment, 1.00mol of PC s vapour was heated in a closed S OOdm

3

flask at SOO

until equilibrium had been established.

The gases in the flask were then rapidly cooled, causing the formation of crystals of

pels

and liquid PCl3 The chlorine gas present was pumped away and collected.

The amount of chlorine collected was x mol.

An excess of water was then very carefully added to the two remaining compounds, under

suitable conditions, causing the following reactions to occur.

PCI

S

+ 4H

5HCl

+ H

3

P0

4

PCl

+ 3H

H l + H

3P

3

You may assume that both H

3

P0

4

and H

3

P0

3

behave as dibasic diprotic) strong acids.

a

Determine, in terms of X the number of moles of H+that will be formed after the addition

of water to the mixture of PCl

s

and PCI

[4)

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he result ing solution was made up to 1.00 dm

3

in a standard flask.

25 cm

3

of this solution

was titrated with 4.00 mol dm-3 NaOH and required 37.4 cm

3

for neutralisation.

b i

Calculate the total amount, in moles, of H ions present in the 1.00dm

3

standard

flask.

II

Use your answers to

3 a

and

3 b i

to calculate the amounts, in moles, of

P I

5

PCl

a

and l

in the original equil ibrium at 500 K.

[ J

e Use your answers to question 2 a and 3 b ii} to calculate a value for K

c

for the

equilibrium.

[2]

[Total: 1Dj

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4 The elements of Group It, magnesium to barium, are metals while the elements of Group VII,

chlorine to iodine, are non-metals.

a I State one physical property of the elements of Group II which shows them all to be

metals.

ii State one trend in the physical properties of the elements of Group VII from chlorine

to iodine, and explain

y

this change occurs.

change .

explanation .

.................. .............................................. ........................ ...................................... [4]

Among the elements of Group IV, those towards the top, carbon to germanium, have very

different properties from those at the bottom, tin and lead.

For example, the melting points show a marked change after germanium.

element

C

Si

I

Ge

Sn

Pb

mp o

>3550

1410

937 232

327

i

b

Carbon, silicon and germanium each form a solid with the same type of structure.

I What type of structure is present in solid carbon, silicon and germanium?

ii Suggest why the melting points these elements decrease from carbon to

germanium.

....................................................................... .......... ............................................. [3]

Carbon and silicon each form a tetrachloride.

l

has no reaction with water;

Si l

4

reacts

violently with water.

e I Write a balanced equation for the reaction of

Si l

with water.

i A

(il) Use the

Data Booklet

to obtain values for the

l

and

Si Cl

bond energies.

C Cl

kJ mor

Si Cl n '

kJ mor?

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(III) Suggest an explanation for the inertness of

CC

4

to water.

..............................................................................................................................[3]

Lead forms two chlorides,

PbCl

and

PbCl

4

When chlorine is passed into a saturated solution of PbCl

in NH

4Cl aq ,

a yellow salt, V, is

formed which has the following composition by mass:

i 46.7 ; H, 1.76 ; N,

6.14 ; Pb 45.4 .

V is ionic with a formula mass of 456. One formula unit of Y contains one type of anion and

one type of cation in the ratio 1:2.

d)

(l) Calculate the empirical formula of Y.

(II) Suggest the formulae of each of the ions present in V.

anion cation .

(iii)

What is the oxidation state of Pb in Y?

(Iv) Suggest the shape of the lead-containing ion.

(5]

When Y is treated with cold concentrated H

S 4

, PbCl

4

is formed as an oily liquid.

(e) By using appropriate values from the

Data Booklet

predict what, if anything, will happen

when a solution of PbCl

4

in hydrochloric acid is added to a solution containing V3+(aq).

[2]

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When O.10mol of K is reacted with an excess of sodium metal 2 4dm

3

of hydrogen are

formed measured at room temperature and pressure.

a Use all of the above information to determine the identity and number of each of the

functional groups present in compound K.

For each functional group you identify explain

how

you came to your decision.

K decolourises aqueous bromine.

for

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5]

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9647 0210 N 11

II

reaction with sodium metal

I

reaction with aqueous bromine

5 Compound K has the molecular formula C

a

2

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b Draw the displayed formulae of all the possible stereoisomers of K which have the

following features.

For

Examin r s

U

They have molecular formula

C

a

2

and give the reactions on page

1

No oxygen atom is attached to any carbon atom which is involved in a double bond.

No carbon atom has more than one oxygen atom joined to it.

For each

structure you draw state the type of stereoisomerism it shows and give

one

further piece of relevant information about it.

You are not required to label functional groups.

]

[Total: 12]

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-111111111111111111111111111111111111111111111111111

12

..

6

Compound W has the molecular formula

7 Cl

It is an aromatic compound which

contains two functional groups.

Data about the reactions of Ware given in the table.

_ ._-

_.....

1 '-

.._

...

_

....

reaction

reagent

result

1

AgN0

3 aq .

warm

I

white solid formed which is soluble in an

i excess of NH

3 aq

,

2

Br

2 aq

Iwhite solid formed which has

M

r

=379.2

in an excess

,

I

I

I

i

.

3

Mn0

4

-/OH-

I

Mn0

4

- is decolourised;

heat under reflux one organic product formed with

M

r

=

138

then acidify

._._.

4 Na colourless gas evolved;

white solid formed which is soluble in H

2O

5 NaOH aq at room colourless solution formed

I temperature

-- _.- - -..-._-.

In this question, when identifying functional groups, your answers should be unambiguous.

8 I

What

is the white solid that is formed in reaction 1?

II Name the funct ional group that reaction 1 shows to be present in W.

iii Based only on reaction 4, give the names of two different functional groups that

could be present in W.

.................................. and .

iv Which of the funct ional groups you have named in III is confirmed by reaction 5?

Explain your answer.

.............................................................................................................................. [5]

b

Deduce the molecular formula of the organic product formed in reaction 3.

[1]

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e i Deduce the molecular formula of the white solid formed in reaction 2

II

What type of reaction takes place in reaction 2?

ill

Explain clearly how the formation of this compound shows that compound W is an

aromatic compound rather than an aliphatic compound

Iv Name the functional group present in W that is confirmed by reaction 2

v

Which other reaction confirms that W is aromatic? Explain your answer

reaction

[6]

d You now have enough information to determine the structural formula of W

i

Draw the fully displayed structure of W

Ii Explain clearly why you have placed each of the two functional groups in their

particular positions

[4]

[Total: 16]

For

xaminer s

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Permission to reproduce Where third-party owned matorial protected by copyright is included has been sought and cleared where possible. Every

reasonable effort has been made

t

the publisher UClES) to trace copyright holders, but II any hems requiring clearance have unwIttingly been included, the

publisher pleased 10make amends at the earliest possible

o p p o r t u n ~

Univol5ity of Carrt>rll1ge International Examlnatlons is part of the Cambridge Assessment Group. Cambridge Assessmem ts the brand name of University

Cambridge Local ExaminaUonsSyndicate UCLES), which Is its a department of Ihe University of Cambridge.