chemistry stpm trial first term 2013

5/27/2018 CHEMISTRY STPM Trial First Term 2013

1/12

CHEMISTRY 962/1

One hour and a half hours

`

Name : ! "orm :

S#MM$TI%E $SSESSMENT

"IRST TERM

ST&M

2'1(

LOGO DAN

NAMA SEKOLAH


2/12

Se)*+on $ [15 marks]

Answer allquestions in this section.

1 C and C atoms are isotopes of caron! "#ic# of t#e fo$$o%in& is t#e same

for t#e isotopes'

$ Stai$it(

, N)c$ear c#ar&e

C N)c$eon n)mer

- *e$ati+e isotopic mass

2

"#ic# of t#e fo$$o%in& )nkno%n or&anic compo)nd %i$$ re$ease a spectr)m as t#e one s#o%n

ao+e'

$ C,H-, C-H1.C C1/H0/- C1/H00

( anadi)m #as t#e e$ectronic confi&)ration of 1s00s00p.2s02p.2d2,s0! "#ic# ion does no*e3ist'

$ O,2. , O2

. C O04 - O2

0

10

.

1,

.

*e$ati+e

intensit(

me/ 0/ ,/ ./ -/ 1// 10/ 1,/ 1./


3/12

0 6#e ener&(7$e+e$ dia&ram for a #(dro&en atom s#o%s se+era$ e$ectronic transitions %it# fre8)encies

f19f29f39f4andf5!

"#ic# of t#e fo$$o%in& statements is are *rueof t#e ao+e dia&ram'

I f1 represents t#e con+er&ence $imit of t#e L(man series!

II f19f2andf3represent $ines in t#e L(man series!

III f4andf5are )sed to ca$c)$ate t#e difference et%een t#e ener&( $e+e$s of

n : 2 and n : ,!

I% 6#e e$ectronic transition off3&i+es a $ine spectr)m t#at corresponds to t#e

re&ion of +isi$e $it!

$ I and II

, Iand I%C IIand III

- IIIand I%

;ased on t#e and t#eor(9 t#e cond)cti+it( of meta$ is d)e to de$oca$i

f1 f2 f3

f4 f5


4/12

"#ic# species is dra%n %it# t#e correct s#ape'

$ [ ? @ ? @ ? ] 7 ,

O O 07

S

O O

C

;

-

H

B

H H

3

6#e dia&ram ao+e s#o%s t#e od(7centred c)ic str)ct)re of a )nit ce$$! Ho% man( atoms are t#ere

in t#e )nit ce$$ ao+e'

$ 1 , 0 C 2 - ,

9 6#e ;o$t


5/12

1' A p#ase dia&ram of %ater is s#o%n e$o%!

O

"#at can (o) ded)ced from t#e p#ase dia&ram'

$ An increase in press)re %i$$ decrease t#e free


6/12

1( "#ic# )nder$ined mo$ec)$e reacts as a Le%is ase'

$ K0O 4 SO2 K0SO,, ;2 4 NH2 H2N!;2C OH7 4 CO0 HCO2

7

- CH2C$ 4 eC$2 CH24 4 eC$,

7

10 6#e so$)i$it( prod)ct9 Kspof ma&nesi)m #(dro3ide in p)re %ater at 05oC is 0!/ 3 1/711mo$2dm7!

"#at is t#e so$)i$it( of ma&nesi)m #(dro3ide %#en an e3cess of so$id ma&nesi)m #(dro3ide is

s#aken in 1 dm2of /!1 mo$ dm72sodi)m #(dro3ide'

$ 0!/ 3 1/712 mo$ dm72

, ,!/ 3 1/710 mo$ dm72

C ,!/ 3 1/711 mo$ dm72

- 0!/ 3 1/7 mo$ dm72

1 6#e p#ase dia&ram of a mi3t)re of t%o $i8)ids B and is as fo$$o%sI

"#at co)$d B and e'

B

$

6ric#$oromet#ane Bropanone

, ;en


7/12

SECTION , [15 marks]

Answer all 8)estions in t#is section!

16 6#e mass spectr)m of a &aseo)s compo)nd is s#o%n e$o%!

4a5 "rite t#e form)$a of ions responsi$e for eac# of t#e peaks $ae$$ed A9 ;9 C and D!

[0 marks]

A I 77777777777777777777777777777 ;I 777777777777777777777777777777777

CI 777777777777777777777777777777 DI 777777777777777777777777777777777

45 iF "rite a possi$e form)$a for t#e compo)nd %it# me +a$)e of 0

[0 marks]

777777777777777777777777777777777777777777777777777777777777777777777777777777777777777777

iiF Name t#e compo)nd

7777777777777777777777777777777777777777777777777777777777777777777777777777777777777777777

4)5 6#e fo)r nat)ra$$( occ)rrin& sta$e isotopes of iron are &i+en in t#e ta$e e$o%!

Determine t#e re$ati+e atomic mass of iron! [0 marks]

*e$ati+e atomic mass 52!, 55!2 5.!, 5!2

*e$ati+e a)ndance J 5!-0 1!-/ 0!1/ /!0-

Bercenta&ea)ndance


8/12

17. 6#e dia&ram e$o% represents t#e ener&( $e+e$s of t#e orita$s in atoms of t#e t#ird period!

(aF ?ndicate t#e t(pe of orita$s at eac# ener&( $e+e$ e$ectrons in t#e dia&ram ao+e!

[0 marks]

45 Dra% and $ae$ a$$ t#e possi$e s#apes of orita$s at t#e ener&( $e+e$9 n : 0!

[, marks]

4)5 ?n t#e ao+e dia&ram9 mark t#e +a$ence e$ectron confi&)ration for p#osp#or)s9 )sin& arro%s to

represent e$ectrons in t#e dia&ram ao+e!

[2 marks]

-

Ener&(


9/12

SECTION C[2/ marks]

Ans%er an(*7o 8)estions in t#is section!

13 4a5 Ammonia is a co$o)r$ess &as %it# a p)n&ent sme$$! ?t reacts %it# #(dro&en ions in acids to form

ammoni)m ions9 NH,4! Dra% a Le%is str)ct)re for ammonia and t#e ammoni)m ion!

[0 marks]

45 6#e H@N@H ond an&$es in ammonia and ammoni)m ion are 1/ and 1/!5 respecti+e$(!

E3p$ain t#e difference in t#ese ond an&$es! [, marks]

4)5 6#e reaction et%een f$)orine and nitro&en dio3ide %as carried o)t at 6 K!

0&F4 0NO0&F 0NO0&F

6#e fo$$o%in& data %ere otained %#en t#e reaction %as carried o)t )sin& different

concentrations of t#e &ases!

"#at is t#e order of t#e reaction %it# respect to

iF f$)orine and nitro&en dio3ide' [, marks]

iiF "rite t#e rate e8)ation for t#e reaction! [ 1 mark ]

iiiF Bropose a possi$e mec#anism for t#is reaction! [, marks]

19! 4a5 Nitro&en mono3ide9 NO can e prepared from t#e reaction et%een nitro&en and o3(&en!

N0&F4 O0&F 0NO&F H : 41-/!5 k

State #o% iF Kcand iiF t#e amo)nt of NO %i$$ c#an&e %#en an e8)i$iri)m mi3t)re of N09 O0and

NO is s)ected to t#e fo$$o%in& c#an&es!

iF More O0is added

iiF 6#e +o$)me is increased

iiiF 6#e temperat)re is decreasedi+F A cata$(st is )sed

[- marks]

45 Caron mono3ide can e )sed to red)ce steam to #(dro&en!

CO&F 4 H0O&F H0&F4 CO0&F

0!0/ mo$ of CO&Fand 1!1 mo$ of H0O are p$aced in an empt( 1!// dm2 f$ask at 6 C! After

e8)i$iri)m %as reac#ed9 t#e concentration of CO %as /!- mo$ dm 72! Ca$c)$ate

iF t#e concentration of H0O&Fat e8)i$iri)m [0 marks]

iiF t#e +a$)e of Kcat 6 C for t#e ao+e reaction [0 marks]iiiF t#e +a$)e of Kcat 6 C for t#e reaction9

H0&F4 CO0&F CO&F4 H0O&F [2 marks]


10/12

2'! 4a5 iF "#at do (o) )nderstand ( t#e term so$)i$it( prod)ct' [0 marks]

iiF "rite an e3pression for t#e so$)i$it( prod)ct of ma&nesi)m #(dro3ide9 M&OHF0!

[0 marks]

45 A 05!/ cm2samp$e of sat)rated9 a8)eo)s ma&nesi)m #(dro3ide re8)ired 1!0 cm2of /!/5/ mo$ dm72

#(droc#$oric acid for ne)tra$isation! Ca$c)$ate

iF t#e #(dro3ide ion concentration of t#e sat)rated so$)tion9 [0 marks]iiiF a +a$)e for t#e so$)i$it( prod)ct of ma&nesi)m #(dro3ide9 statin& t#e )nits!

[0 marks]

4)5 6#e )ffer s(stem9 H0BO,7 HBO,

07in $ood #e$ps to keep t#e pH of $ood at ao)t !,/!

iF Ca$c)$ate t#e [H0BO,7] [ HBO,

07 ] ratio at t#e norma$ pH of $ood!

[KaH0BO,7 I .!0 3 1/7-mo$ dm 72] [2 marks]

iiF sin& a s)ita$e e8)ation9 e3p$ain %#at #appens %#en=

?F a sma$$ amo)nt of stron& acid is added to t#is )ffer s(stem!

??F a sma$$ amo)nt of stron& ase is added to t#is )ffer s(stem!

[, marks]

END OF QUESTION PAPER

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chemistry stpm trial first term 2013

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