9701_s07_ir_31

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SP (SLM) T39273/6

© UCLES 2007 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Subsidiary Level and Advanced Level

The Supervisor’s attention is drawn to the form on page 7 which must be completed and returnedwith the scripts.

If you have any problems or queries regarding these instructions, please contact CIEby e-mail: [email protected] phone: +44 1223 553554by fax: +44 1223 553558stating the Centre number, the nature of the query and the syllabus number quoted above.

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CHEMISTRY 9701/31

Paper 31 Practical Test May/June 2007

CONFIDENTIAL INSTRUCTIONS

Great care should be taken to ensure that any confidential information given does not reach thecandidates either directly or indirectly.

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Safety

Supervisors are advised to remind candidates that all substances in the examination should be treatedwith caution. Only those tests described in the question paper should be attempted. Please also seeunder ‘Apparatus’ on the use of pipette fillers, safety goggles and plastic gloves.

In accordance with COSHH (Control of Substances Hazardous to Health) Regulations, operative in theUK, a hazard appraisal of the examination has been carried out.

Attention is drawn in particular, to certain materials used in the examination. The following codes areused where relevant.

C corrosive substance F highly flammable substance

H harmful or irritating substance O oxidising substance

T toxic substance N dangerous for the environment

The attention of Supervisors is drawn to any local regulations relating to safety and first-aid.

‘Hazard Data Sheets’, relating to materials used in this examination, should be available from yourchemical supplier.

Before the Examination

1 Access to the question paper is NOT permitted in advance of the examination.

2 Preparation of materials

Where quantities are specified for each candidate, they are sufficient for the experimentsdescribed in the question paper to be completed.

In preparing materials, the bulk quantity for each substance should be increased by 25% as spare material should be available to cover accidental loss. More material may be supplied ifrequested by candidates, without penalty.

All solutions should be bulked and mixed thoroughly before use to ensure uniformity.

Every effort should be made to keep the concentrations accurate to within one part in two hundredof those specified.

Supervisors are asked to carry out any confirmatory tests given on pages 4 and 5 to ensurethe materials supplied are appropriate.

If the concentrations differ slightly from those specified, the Examiners will make the necessaryallowance. They should be informed of the exact concentrations.

3 Labelling of materials

Materials must be labelled as specified in these instructions. Materials with an FA code numbershould be so labelled without the identities being included on the label. Where appropriate theidentity of an FA coded chemical is given in the question paper itself.

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4 Identity of materials

It should be noted that descriptions of solutions given in the question paper may not correspondexactly with the specifications in these Instructions. The candidates must assume thedescriptions given in the question paper.

5 Size of group

In view of the difficulty of the preparation of large quantities of solution of uniform concentration,it is recommended that the maximum number of candidates per group be 30 and that separatesupplies of solutions be prepared for each group.

Apparatus

1 In addition to the fittings ordinarily contained in a chemical laboratory, the apparatus and materialsspecified below will be necessary.

2 Pipette fillers (or equivalent safety devices), safety goggles and disposable plastic gloves shouldbe used where necessary.

3 For each candidate

2 × 50 cm3 burettes2 × burette clamps2 × stands2 × funnels for filling burettes1 × 250 cm3 graduated (volumetric) flask, labelled FA 31 × 250 cm3 conical flask

1 × 25 cm3 measuring cylinder (a 25 cm3 cylinder is specifically required, not a larger or smallercylinder)1 × 25 cm3 pipette1 × pipette filler (or equivalent safety device)1 × white tile1 × wash bottle containing distilled water1 × weighing bottle1 × plastic cup (preferably foamed plastic or expanded polystyrene) to hold at least 100 cm3

1 × 250 cm3 beaker (to support the plastic cup)1 × 50 cm3 measuring cylinder1 × –10 °C to 110 °C by 1 °C thermometeraccess to a balance weighing to 0.1 g or better2 × 100 cm3 beakers2 × stirring rods2 × test-tubes5 × boiling-tubes1 × test-tube rack1 × test-tube holder1 × Bunsen burner1 × tripod and gauze1 × heat proof mat2 × teat/squeeze pipettespaper towels

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C h e m i c

a l s R e q u i r e d

1

I t i s e s

p e c i a l l y i m p o r t a n t t h a t g r e a t c a r e i s t a k e n t h a t t h e c o n f i d e

n t i a l i n f o r m a t i o n g i v e n b e l o w d

o e s n o t r e a c h t h e c a n d i d a t e s

e i t h e r d i r e c t l y o r

i n d i r e c

t l y .

2

P a r t i c u

l a r r e q u i r e m e n t s

h a z a r d

l a b e l

p e r

c a n d i d a t e

i d e n t i t y

n o t e s

( H a z a r d s g i v e n i n t h i s c o l u m n a r e f o r t h e r a w m a t e r i a l s . )

[ H ]

F A 1

1 5 0 c m

3

3 . 4 0 g d m

– 3

a n

h y d r o u s N a 2

C O

3

a q u e o u s s o

l u t i o n o f a n h y d r o u s s o d i u m c a r b o n a t e ,

N a 2

C O

3 [ H ] , 3 . 4

0 g d m

– 3

[ H ]

F A 2

5 0 c m

3

0 . 5 0 m o l d m

– 3

H C l

P r e p a r e t h i s s o l u t i o n b y d i l u t i n g 4 5 c m

3 o f

c o n c e n t r a t e d a c i d [ C ] ( 3 5 %

w / w

; a p p r o x i m a t e l y

1 1 m o l d m

– 3 ) t o 1 d m

3 .

C h e c k a n d

a d j u s t t h e c o n c e n t r a t i o n o f t h e

a c i d i n t h e f o l l o w i n g w a y .

•

P i p e t t e

a t o t a l o f 5 0 . 0 c m

3 o

f F A 2 i n t o a 2 5 0 c m

3 g

r a d u a t e d f l a s k a

n d m a k e u p t o

2 5 0 c m

3 w

i t h d i s t i l l e d w a t e r .

•

P i p e t t e

2 5 . 0 c m

3 o

f F A

1 i n t o a c o n i c a

l f l a s k a n d a d d a f e w d r o p s o f m e t h y l o r a n g e

i n d i c a t o

r .

•

T i t r a t e F A 1 a g a i n s t t h e d i l u t e d F A 2 . T

h e t i t r e s h o u l d b e i n t h e r a n g e

1 5 . 5 – 1 6 . 5 c m

3 .

•

C a l c u l a t e a n d c a r r y o u t a n y n e c e s s a r y

a d j u s t m e n t t o t h e c o n c e n t r a t i o n o f h y d r o c h l o r i c

a c i d i n F A 2 .

m e t h y l

o r a n g e

i n d i c a t o r

1 0 c m

3

m e t h y l o r a n g e

i n d i c a t o r

( p H r a n g e 2 . 9

t o 4 . 6

)

U s e c o m m e r c i a l l y p r o d u c e d s o l u t i o n o r p

r e p a r e f r o m

s o l i d b y d i s s o l v i n

g 0 . 4 g o f s o l i d

i n d i c a t o r i n

2 0 0 c m

3 o

f e t h a n o l [ F ] a n d m a

k i n g u p t o 1 d m

3 w

i t h d i s t i l l e d w

a t e r .

I n d i c a t o r m

a y b e m a d e a v a i l a b l e i n c o m m u n a l d r o p p i n g b o t t l e s .

[ H ]

F A 4

1 0 g

a n

h y d r o u s s o d i u m

c a

r b o n a t e ,

N a 2

C O

3

[ H ]

F A 5

1 2 0 c m

3

2 . 0 m o l d m

– 3

H C l

P r e p a r e t h i s s o l u t i o n b y d i l u t i n g 1 9 0 c m

3 o f

c o n c e n t r a t e d a c i d [ C ] ( 3 5 %

w / w

; a p p r o x i m a t e l y

1 1 m o l d m

– 3 ) t o 1 d m

3 .

[ H ]

F A 6

2 g

s o

l i d z i n c

c a

r b o n a t e ( b a s i c )

D i f f e r e n t f o

r m u l a e m a y b e o f f e r e d f o r t h e “ b a s i c c a r b o n a t e ” t h e m o s t

c o m m o n b e i n g

[ Z n C O

3 ] 2 [ Z

n ( O H ) 2 ] 3 .

A n y c o m b i n a t i o n o f c

a r b o n a t e ,

h y d r o x i d e a n d w a t e r

i s a c c e p t a b l e .

[ T ]

F A 7

2 g

s o

l i d c o p p e r ( I I )

c h

l o r i d e ,

C u C l

2 . 2

H 2

O

T h i s s o l i d s h o u l d b e p r o v i d e d t o c a n d i d a

t e s i n a s t o p p e r e d c o n t a i n e r

a s i t i s l i k e l y t o

a b s o r b m o i s t u r e f r o m

t h e a i r .

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T h e s t a n d a r d b e n c h r e a g e n t s s p e c i f i c a l l y r e q u i r e d a r e s e t o u t b e l o w

. I f n e c e s s a r y , t h e y m a y b e m a

d e a v a i l a b l e f r o m

a c o m m u n a l

s u p p l y : h o w e v e r ,

t h e a t t e n t i o n o f t h e I n v i g i l a t o r s s h o u

l d b e d r a w n t o t h e f a c t t h a t s

u c h a n a r r a n g e m e n t m a y e n h a n c e t h e o p p o r t u n i t y f o r m a l p r a c t i c e b e t w e e n

c a n d i d

a t e s .

h a z a r d

l a b e l

i d e n t i t y

n o t e s

( H a z a r d s g

i v e n i n t h i s c o l u m n a r e f o r t h e r a w m a t e r i a l s . )

[ C ]

d i l u t e n i t r i c a c i d

2 . 0 m

o l d m

– 3

H N O

3

D i l u t e 1 2 8 c m

3 o

f c o n c e n t r a t e d ( 7 0 %

w / w ) a c i d [ C ] [ O ] t o

1 d m

3 .

[ C ]

a q u e o u s s o d i u m

h y d r o x i d e

2 . 0 m

o l d m

– 3

N a O H

D i s s o l v e 8 0 . 0 g o f N a O H [ C ] i n e a c h d m

3 o f s o l u t i o n .

C a r e – t h e p r o c e s s o f s o l u t i o n i s e x o t h e r m i c a n d a n y

c o n c e n t r a t e d

s o l u t i o n i s v e r y c o r r o s i v e .

[ H ]

a q u e o u s a m m o n i a

2 . 0 m

o l d m

– 3

N H

3

D i l u t e 1 1 2 c m

3 o

f c o n c e n t r a t e d ( 3 5 %

w / w ) a

m m o n i a [ C ] [ N ]

t o 1 d m

3 .

4

T h e r e

a g e n t s , m a t e r i a l s a n d a p p a r a t u s t o t e s t t h e g a s e s l i s t e d i n t h e s y l l a b u s m u s t b e a v a i l a b l e

t o c a n d i d a t e s .

I f n e c e s s a r y , t h e y m a y b e m a d e

a v a i l a b

l e f r o m a c o m m u n a l s u p p l y : h o

w e v e r , t h e a t t e n t i o n o f t h e I n v i g i l a t o r s s h o u l d b e d r a w n t o t h e

f a c t t h a t s u c h a n a r r a n g e m e n t m a y e n h a n c e t h e

o p p o r t u n i t y f o r m a l p r a c t i c e b e t w e e n c a n d i d a t e s .

h a z a r d

l a b e l

i d e n t i t y

n o t e s

( H a z a r d s g i v

e n i n t h i s c o l u m n a r e f o r t h e r a w m a t e r i a l s . )

[ H ]

l i m e w a t e r

s a t u

r a t e d a q u e o u s c a l c i u m

h y d r o x i d e ,

C a ( O H ) 2

P r e p a r e f r e s h l i m e w a t e r b y l e a v i n g d i s t i l l e d

w a t e r t o s t a n d

o v e r s o l i d c a l c i u m

h y d r o x i d e [ H ] f o r s e v e r a l

d a y s , s h a k i n g

o c c a s i o n a l l y .

D e c a n t o r f i l t e r t h e s o l u t i o n .

[ T ] [ N ]

a q u e o u s p o t a s s i u m

d i c h r o m a t e ( V I )

0 . 1 m

o l d m

– 3

K 2

C r 2 O

7

D i s s o l v e 2 9 . 5 g o f K

2 C r 2 O

7 [ T ] [ N ] i n e a c h d m

3 o

f s o l u t i o n

w h i c h s h o u l d

c o n t a i n a b o u t 1 0 %

d i l u t e s u l p

h u r i c a c i d [ H ] .

T h e u s e o f p l a s t i c g l o v e s m a y b e c o n s i d e r e d t o p r e v e n t

c o n t a c t w i t h s k i n .

r e d a n d b l u e l i t m u s p a p e r

p l a i n f i l t e r p a p e r s t r i p s f o r u s e w i t h

d i c h r o m a t e

w o o

d e n s p l i n t s

t h e a p p a r a t u s n o r m a l l y u s e d i n t h e

C e n t r e f o r u s e

w i t h

l i m e w a t e r i n t e s t i n g f o r c a r b o n

d i o x i d e

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Responsibilities of the Supervisor during the Examination

1 The Supervisor, or other competent chemist must carry out the experiments in question 1 andquestion 2 and complete tables of readings on a spare copy of the question paper which shouldbe labelled ‘Supervisor’s Results’.

This should be done for:each session held and each laboratory used in that session, and each set of solutionssupplied.

N.B. The question paper cover requests the candidate to fill in details of the examinationsession and the laboratory used for the examination.

It is essential that each packet of scripts contains a copy of the applicable Supervisor’sResults as the candidates’ work cannot be assessed accurately without such information.

2 The Supervisor must complete the Report Form on page 7 to show which candidates attended

each session. If all candidates took the examination in one session, please indicate this on theReport Form. A copy of the Report Form must accompany each copy of the Supervisor’s Resultsin order for the candidates’ work to be assessed accurately.

The Supervisor must give details on page 8 of any particular difficulties experienced by a candidate,especially if the Examiner would be unable to discover this from the written answers.

After the Examination

Each envelope returned to Cambridge must contain the following items.

1 The scripts of those candidates specified on the bar code label provided.

2 A copy of the Supervisor’s Report relevant to the candidates in 1.

3 A copy of the Report Form, including details of any difficulties experienced by candidates (seepages 7 and 8).

4 The Attendance Register.

5 A Seating Plan for each session/laboratory.

Failure to provide appropriate documentation in each envelope may cause candidates to bepenalised.

COLOUR BLINDNESS

With regard to colour-blindness – a minor handicap, relatively common in males – it is permissibleto advise candidates who request assistance on colours of, for example precipitates and solutions(especially titration end-points). Please include with the scripts a note of the index numbers of suchcandidates.

Experience suggests that candidates who are red/green colour-blind – the most common form – donot generally have significant difficulty. Reporting such cases with the scripts removes the need for a‘Special Consideration’ application for this handicap.

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9701/31

REPORT FORM

This form must be completed and sent to the Examiner in the envelope with the scripts.

Centre Number ........................................................ Name of Centre .....................................................

1 Supervisor’s Results

Please submit details of the readings obtained in Question 1 and Question 2 on a spare copy ofthe question paper clearly marked ‘Supervisor’s Results’ and showing the Centre number andappropriate session/laboratory number.

2 The index numbers of candidates attending each session were:

First Session Second Session

3 The Supervisor is required to give details overleaf of any difficulties experienced by particularcandidates, giving names and index numbers. These should include reference to:

(a) any general difficulties encountered in making preparation;

(b) difficulties due to faulty apparatus or materials;

(c) accidents to apparatus or materials;

(d) assistance with respect to colour blindness.

Other cases of hardship, e.g. illness, temporary disability, should be reported direct to CIE on thenormal ‘Application for Special Consideration’ form.

4 A plan of work benches, giving details by index numbers of the places occupied by thecandidates for each experiment for each session, must be enclosed with the scripts.

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Report on any difficulties experienced by candidates.

Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Everyreasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the

publisher will be pleased to make amends at the earliest possible opportunity.

University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of

Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

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