chem jan 06
TRANSCRIPT
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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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