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fftUNiVERSITi

cD

T

)URSE

'TE/lE

TEKNOLOGI

ECFOOI4 CHEMISTRY

30 MAY2006 TUESDAY)

9.00AM- 12.00NOON 3 hours)

PETRONAS

INSTRU

SECTIOSECTIO

:TIONS O CANDIDATES

I A : Answer LLquestions n he OMRsheet.I B : 1. Answer OUR 4)out of SIX 6)questi s in he Answer

Booklet.

Begin EACH answer on a new page.

Indicate learly nswers hat are canc ed, f any.

Where applicable, how clearly teps (en in arriving t

the solutions nd ndicateALL assumF, ns.

Do not ooen his Question Booklet nti nstructed.

2.

A

There are TWENTY-FOUR 24) pages

includinghe cover age and appendices.

in this , uestion Booklet

Universiti Teknoloqi PETRONAS

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"d

ECF OC i

SECTIONB

[60 Marks] '. i

AnswerFOUR 4) ou, of SIX (6)questions.

d... Lead o ide, Pblz s a compound hat has a very ow solubilityn

water. he precipitate f Pblz can be prepared y mixing he

solution of lead nitrate, b(NO3)2nd potassium odide, l. In onO

reaction 5.00mLof 2.00 M solution f lead nitrate nd 65'50 n =

of 2.50M solution fpotassiumodide ere mixed.

D :termine he limitingand excess eactants n the abov.q

re action. ustify ou ranswer.

14mark l

V,hat s the actualweightof Pblz precipitate roduced f th+

p ,rcentage ield f the eaction s 86.5%?

[3 mark I

C rlculate he molarity f NO3- ons n the resulting mixtur .

A sume hat he otal olume s 140.50mL.[4 mark I

A mixtur of gases n a 18.50-L essel t 15"C onsists f 5.55g t\

C'2, .92 g of N2,and 1.75g of Hz.Calculate he partial ressurc

(inatm) 'fN2and Oz n he gas mixture.

[4 mark

il .

i l1 .

b.

I

tc

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F-

aL. A new ant imalar ia l

1. .

analysis, .2394 g

changed all of the

volume f 18.90 mLV

a. Calculate he

-^fAd4 A

EUI- UU I+

l rugcompound ontains , H, N and O' In a chemical

amo|ewasmadetoundergoaseriesofreact ionsthat

ritrogen n the compound o Nz gas' The gas had a

and a pressure f 739.9 orr.

-r .

percentage by mass) of nitrogen n the sample'

[4 rnarks]

b. When 6.478 mg of the compound as burned n pure oxygen'

17.57 g of coz and 4.319mg of Hzo were obtained. hat are he

percentages ymass)of C and H n hiscompound?

[5 marks]

Determine h I empiricalormula f his compound'

[4 rnarks]

The molar n as s of the comPound as

What s ts m rlecularormula?

found to be 324 g mol-1.

r ' . , )-f

i

d.

\St\s

to

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Platinum rYstallizesn he

below. he adius fa Plat

'i.: : -\i!-

t. '

\ ._ . - i--

'* , ,"{qf#,

FIGU

iii. Ina solution fLiCl n water'

rf^r- an{. AT

:ype of unit cel l l lustrated n:IGURE Q3

rum atom is 139 Pm.

-:- \-ri :i il:,\--'i Li l

i#'4i.,,''..-r, #/ *r*i-

't{:il'#.:t5l.g-. n

*'&J#f erT,.ft '.!A:{i'r:;+ :8;w u;#

IE Q3

l l .

i l t .

What s the mass of I unitcellof platinum?[3 marks]

What s the ength $an edge of the platinum ni t :ell?

[2 marks]

What s the density i platinum'

,4 marksl

Which YPe f intermolecul

the ollowing Ystems?

r force s the most mportan or each of

Between ropane, jHemoleculesn iquid ropa e'

[1 mark]

ii . Between HzO and CHgOH molecules n a mi ' ur e of the

l iquid.[1 mark]

[1mark]

b.

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tv. Between Oz and HzO molecules hen

water.

ECFOO14

Oz is dissolved n

[1 mark]

c . Arrangethefo | |owingsubstancesintheorderof increasingboi | ingpoint.

CHgOH, e,CHgOCHs' Oz[2 marks]

18

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a-

ECF OO14

lt requires photonwith r minimum nergy l 4 .41 x10-1sJ o emit

electrons rom sodium me al.

What is the requied minimum requency of l ight to emit

electrons rom sodi tm via the photoelectric ffect?

[2 nrarks]

i l t .

i l.

il .

rgthof this ight?

[2 rnarks]

What s the maxin' m possible inetic nergy {the emitted

electrons f sodium irradiated ith ightof 439 nm?

[2 marks]

Draw he Lewis ot tructure or he molecule zCN2.

What s the wavele

Calculate he ormaHcAJ

b- D-

b.t l - r. - H

charges or each atom n thQ tructure.

:i,r ,[f larlsJ

for cyanate on , NCO- and

[2 rnarks]

[5 marks]

Draw all the possike structuresdetermine he best .tructure.

, . .1r \ /_\ ._\

.-l-_.-'\ -

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5.

ECr 1014

Sodium cl >ride, NaCl, is widely used in the industr ia l roduct ion f

chemicals rch as NaOH, HCIand Clz. n the Chlor-alkali rocess, fJoOH,

Hz and ClzTre ormed hrough he ollowing eaction:

2Na( (aq) + 2H2O(l) i+ 2NaOH(aq) Hz(g) + Clz(g)

a. ls r noving an electron rom chlorine tom an exotherryic r

endr rermic rocess?

[1 rark]

Both Na and Cl are in the third ow of the periodic able. hich

elen nt has he higher irst onization nergy? xplain ouran ver.

[2 n rrks]

Write he expression or molar concentration quilibrium on tant,

K, fclr he above eaction.

[2 n rrks]

d. Wha willhappen f the volume f the reaction essel s decie; ;ed?

Explzn youranswer ccordingo Le Chatdlier's rinciple.

[3 n rrks]

e. ln ti ; process, Clz_and Hz are collected separately h ugh

hydrc Tsis in order to prevent explosive recombinatior At

equi l r ium,0.5850 g Cl2 s col lected n a 15.00 tankat 225"C.

Assu ring hat at equilibriumhe reaction ields72% Cl2anO 5%Hz, h ,w many grams of Hz are actually being produced ; thisproce s?

[6 n' rks]

:: i : '

-]-

i

Name ONE method o increase he yieldof Clz.

[1 r ark]

Lt) .

c.

ZU

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F

ldentifywhether

dissolved n water

i . LiH

ECF OO 4

e fol lowing ompounds re acidic or basic when

State he reason.

[2 marks]

i i . HBr

[2 marks]

Carbonate on,COs2- s being sed o make a basic olutionn the

laboratory. n a 2.5-L container, ertain amount of COg2- s

dissolvednwater'To ake solution fpH 10.70 t25"C.

i. Write he n:t equation or the reaction hat orms he OH

ions n solul'on.

[3 marks]

ii. What s the6:oncentration f the OH ion n he solution?

[3 marks]

lf the Ko value or COg2- s givenas 1.8 x 10-4, ow many

moles f COg2- re equired o make his solution?

[5 marks]

- :ND OF PAPER-

b,

+

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