Spm Trial 2009 Che Ans Hlsel

papercollection

SU1.fT

4541/1

I'PD IHJLU LANGAT, SELAN(;OR TRIAL SI'M 2009. FOR PAPER 2

Isotopes are atoms (of the samc elemcnt) ,vith the same ",/ncr.'"" number but dirferent numbcr of ncutrons/nucleon

Skcma .Jawapan Kcrtas I KilHia PerclliJaan SPM 2009 Daerah Buill Langat, ScJangor.

-

I

o o -~

19, III

20 21.

Ikcomcs

the

IV

TCIll[Jcratnrc fC

25.

correct mclting

I A

n

-+----------t---l_~

I-------..... Time / min ___ ____________._ _ _ _ __ ~

papercollection

yestcd allswer starch, anyone

tll\! bacteria bCCOlll\!

(c)

blue solu~on will fadel blue colour change to colourless number of coppcr(ll) ions in the solution decreases. I'fhe copper ions have been discharge at the electrode by receiving two electron to become copper atoms I metal

Cti- +

I (0

Marks

From zinc to co er Zinc is more electropositive than position of zine is higher than copper in the elctrochemical series allow the movement of the ions through the solution in the

2e

-7

._--­ +

n reads with the H • iOlls ill (lcidic form insoluble long ..:hain filttv acid

2

1

_­

C;

Zinc

2 C1\!aning agcnt

...

2e

and copper arc further apart than zinc and copper in the electrochemical series therefore greater voltage will be roduced if ma Ilesium is used in lace of zinc Total

3

..

1

­

papercollection

----

ested answer +1

No 4

---------­ -----­

o + Mg

(b)

---+

t-- -ti i;)T~;:-;;;::;;;:;:;:;;;;--~:1;id -ox-i-dati~~

carhonate

time. (i) I Iron (II)

- ---jIo­

ZnC01

+wi Oxidat~Jl~-

Fe2+ loses electron I oxidation numher of iron increases to -I 3 ; cold

+e

the gns into lime water

lime water tllrned (ii)

-

10

I No

4

papercollection

---

~sted

Answers

I2c of reaction Exothennic

1-1

II

I

II

Cold pack

I

C -- C

[1~C

Endothennic

[I

I

H

(b)

( c)

II

(ii)

I II n

II

I[

I I c==c I

C--H

I

II

II

I

-- {

(i)

II

Energy

=

100 x 4.2 x32

9.20 = 0.20 mol 46 Burning 0.20 mol of ethanol releases 13440 J Burning I mol ofetanol releases = 13440 67200 J 0.20 The heat of combustion is 67.2 kJ

I I[ I-

1

1+ 1

mcEl

Number of moles of ethanol

H

1+1

Use the wind-shields Place the flame of ethanol close to the copper Clm Stir the water constantly The copper can is heated directly without using wire gauze Weigh the lamp and wick instantly before and after the activity Copper CaJ1 is used

=

_(~IH 1 I

i

Marks

Uses Warm hands and feet in the cold weather I Lessen the ain ofachin muscle Reduce the temperature when having fever I reduce pain in sweUings from sporting injuries

13440 J

=

67.2 kJ

1 1

(iii)

% ofcarbon in A _,~_~c_'--_ _ _ _

X 100%

The heat of combustion of ethanol is higher than methanol Ethanol has more carbon and hydrogen atoms per molecule More carbon dioxide molecules are formed as product More hcat is rdeaseJ during the formation of bonds

85.7%

(12 X4) + (\ X8) % of carbon in B -'-"":-'-"---'-_ _ _ _ X 100% (12 X 4)1 (1 X 10)

82.7%

Pcr(;el:t.~!c\c of -=,~)o[l~ n:.ass in Ai_s~-=-_____._

Tolal

7

(,

1 1 1 1

papercollection

Suggested Answers

2K(Wr_+-B~0~y

-----­

r---·T----~

Isomer l-I

H H II

C

C

I

I

OH

1+ I

Propan-2-o1

1+ 1

II

1

I

H-C-C-C-H I

Propan-l-ol

1

H II

I

C

Atomic size of PotaoS[llm is the biggest. Distance between the nuclells and valence electron is the furthest Attractive forces between the Ilucleus and valence electron is the weakest The easiest to release its valence electron

I

II OF

arrangement of atom P an'angement for atom Q is 2.8.7 To achieve the octet II stable
Max_ Notes: I Label the nuelells and correct charges 2. Correct number of shells and eleetrom

.j

ElectrOll arrangement of Q is 2.8.7 and the electron arrangement f()r

R is2A To achieve the octet II stable arrangement atom R shares electron with atom Q One atom of R contributes 4 electron and each atom of 0 contributes I electron 1 atom orR shares electron with 4 atoms of 0 II Notes: I. Share 4 pairs of electron. All atoms have 8 valence electrons 2. Label the nucleus

Q

Max 4

papercollection

9 with tlilits of graph::c hail

(ii)

Total hydrogen gas volume (em 3 )

paper)

Translcr all points Draw a smooth curve Rate of readioll

120 s 0.25 cm J

30

s·1

graph

20

Rale of reaction at 120s Corrcct answer

(0.11

O.

10

increaces Thc frequency of the collisions belween the particles illcreases The frequcncy of c1Tectivc collisions between the particles in,'..',,,,," The rate of reaction is higher

Time (s)

o

30

GO

90

120

ISO

1 1

eupboard.

Bactcrial growth II adivily is ~iower.

Bacteria prouuce:; less toxic. Food stored in the lasts longer II Rale of lood is lower

10

1

1

11

180

210

270

papercollection

Answers -,--':-.'-,---c--f-----:---::--------

_S~gested Answers I. a)

Rubric Able to record all 5 readings with one decimal place and unit. Answer: 0.0 s 30.0 s 60.0 s 90.0 s 120.0 s cm} cm) tm 3 6.4 cm) 7.0 cm 3 Able to record all 5 readings correctly without unit and decimal placeIJ readings correctly with one decimal pl3Cc and unit. ~------

Soft II Easily bent 2

Apparatus: Weight, ruler, retort stand Materials: Steel bal!, bronze block, copper block Procedure: I. A steel ball is ccllotaped onto the surface of the copper block_ 2. A weight of I kg is hung at a height of I m from the steel ball. 3. The weight is dropped onto the steel ball. 4. The diameter ofthe dent formed on tile:; copper block is measured. 5. The experiment i~ repeated using the bronze block. , I

I

Rubric to construct a suitable table with title and readmgs with unit. -----~----

I

I S02

+ thO Reactants Product

6.4

2

H2S0] II SO] + H 2 0

Readi I1 g:211 2.2 4.2 5.6 - -

6.4 120 7.0 Able to construct a table with at least 2 columns and 2

H 2S04 .1 1

I

(ii) Lowers the pH of water in ponds and livers Aquatic life dies Increase the acidity of the soil Plant dies Leaches the minerals and nutrients of the soil (decreaces the fertility of the soil) Corrodes buildings and metals structures

1 I

o

1 1

1 Max. 5

Total

12

120.0 7.0 Able to construct a tnblc wilh title nr unit with reading

()

Max. 10 --7

____ R_ea_dings 1---~-_--1 2.2 4.2 5.6

30.0 60.0

Observation: The diameter ofthe dent formed on the copper block is larger shows alloy bronze is harder than copper.

(ii) I Explanation: I. The atoms in copper are arranged in an orderly manner causing the atoms to slide easily. 2_ The tin atoms in bronze disrupt the orderly arrangement of copper atoms. 3. Making it difficult for the copper atoms to slide over each other. (c) (i)

b)

I

20 2

----~

papercollection

c)

.-

to classify allihe 2 pairs of ions corredly. Answer:

ll__~

i- -s:;,~ d'dm~d'Te.,_ __ I I II'

2

tVl'

--.-l

2

disch
Able to have an idea of stating a hypothesis. Answer: Ions discharged. at electrodes No response I rncorrect response

d)

o

Variables Manipulated

f) , Score

_nl

,

Rubric Able to state the correct hypothesis Answer: Type of electrode will affect the choice of ions to be discharged. Able to state a hypothesis but inaccurately. Answer: Different electrode will affect the iollS to be

Score 3

e)

.-.-'li~~le to slate the cor~ c~l-i-nf.-e"-~- ':n. :.bc-,-,r!,-~

Rubric

Type of electrodes/pairs of carbon electrode and pairs of cOEEer electrodes

.

AIlswer: (XI' ions are selectively discharged at (I11mle producing oxygen gas because il ,:, lower lhat 50/' ions III . the Electrochemical series. Able to state the iufef(;nee but accurate.­ . Answer: Ofr ions an: discharged at anode, pro(Juelllg oxygell ,ga,:". AllY suit espoll~e i ions arc dischafged/Ox~n ar~ produced ..... __ re';n"n<", I inc()[re~ respons<~ _____._ _._. ___.___

less

I

Scorc 3 marks Score 2 marks Score I marks Score 0 marks

lor for for for

all 3 correct response.

any 2 correct response.

any L correct response.

no response or incorrect response.

e) i) g)

Score 3

Score 3 Able to state the observation coreeetly Sugessted Ul1s\ver: 0) At electrode R: Copper electrode becomes thillllcri

Able to state aU 4 ions correctly

2 0

smaller/mass of copper electrode dl:creases At ekdro',k S: Brown solid

tI,'nn~it,·,

mereases.

.'

.

3

papercollection

h) Rubric Able to calculate the volume, number of mole and ma')s of oxygen released at time 120 seconds correctly,

Sugessted Answer:

Volume of oxygen gas = 4,8 ern] No of mole of oxygen ga~ = 0.0002/2x I0-4 Mass of oxygen gas 0.0002 x 32

~

-

-~

Qllestion no 2 (a} tAble

10

stale the ;lj~;'; of th~ experiment correctly]

J

I Sample answer: I To dctenninc the positioll of carboll in the reaelivity series of

I metals, -'-~

~ ~--

---------

-~-- -~-- -~--­

II [Able to stale the aim of the experiment less correctly]

2

I Sample answer:

I Where is the i)

2(b)

j)

Score J

I I

Able to predict the changes in mass for electrode R~S conclusion correctly. Answer: Electrode R: mass decreased Electrode S: mass increa<;ed Conclusion . Copper anode dissolved forming CU2f and copper deposited at the cathode

of carbon in the reactivity series of

To determine t~ositiOll of carbon. [Ab"e to give an id~;~;[ij:;;: ai~loftl1~experil1le~tJ--­ Sample answer: The position of carhon, [No response~1! wn)!lg~~p~lI2!:'.eL [Ahle to state the hypothesis Sample answer:

If carbon can reduce the metal oxide, then carbon is above the

metal in the reactivity scries of metals.

- [Abl~t;:;;;t;k- the hypothesis lcs-s-c-(-)rr-C-~c-t-;-ly-C:]-­

3

Sample answer:

If carbon reacts with a metal oxide, carbon is more reactive.

~ [Ablc(;;- giv~;nidea of hypothe~is 1-----­

2

Sample answer: Some met~l oxides react with carbon, _____ ~_ N~ ~<)£oI.l:>e or "/rong respo~~ _ _~ (Able to slale all three variables correctly]

~

~____ _

Sample answer: Manipulated variable' type of metal oxides// aluminium I oxide and iron(IlI) oxide ! Responding variable: reactivity of metal Constant variables: carbon powder [Able to state any two variables correetly1

2

y

0

a

a

3

2

, I ,

k 5

[Able to state anyone variable correctly]

I r - - - - - - - - - - - - - - - -I---'::-~ i [No response oS ",,!ong responseJ

papercollection

!Ql;c~tior~ ll~

!

!,~

I

~

[Able to list the

Marks

uestiOOI no

I 2 (t)

I[

\ble to show the tabulation of data with the correct headings 1d a observations]

2

I

ansVverMixture Carbon + iron (III) oxide Carbon + aluminium oxide

S

-~-

,ide, aluminium '1xid<.:

I ill.rara [liS : I Crucible, tripod slaud, spatula, pipe-day triangle. bUIlSt:1l ~burner

\.Q"

f-::

no-+

- 2 (d) !~[~A-c-b-k-'t-o-'-"-is-( all the SUbs;;lces

I:) uggcsted" ':w'~r' I ~Ja{eria~ ~

ICarbon pov iron rIll)

-----

r--~---

I

Rubri<:;

-

Observation

_ substances and apparatus]

2

,ble to show the tabulation of data with one heading and one mixture]


Suggested answer:

Substance!;! :

Carbon powder, iron (1lI) oxide! aluminium oxide'

s ,ggcstcd answer:

t;

Mixture/substances :a'rbon + iron (III) oxide

Observation

_ gr~ible, tripod SUlll(~ bll!lsell

[Able to list some substances

[No resEonse or wron~ resEonsc] Suggested answer: CarbOil, metal oxide

Total

I bJ2varatus :

cruCibleiany suitable coni~ner, ElHlsen ~~er

_,~~espon:;~~r wr,?ng response] _~ __

2(e) [Able to s,tute all,thc procedure correctly]

t

0

Suggested .U1swer: 3 1. Mix together one spatula of carbon with one spatula of iron(III) oxide ill a crucible. \ 2. Place the crucible on the tripod stand.

3, Heat the mixture strongly.

4. Record the observations. 5. Repeat steps 1 to 4 by replacing iron (III) oxide with f_______ a~lu_m~il~li_ul_11_0~x~~id~e~.____________________________~---- _____ to state steps I, '

I

END OF MARKlNG SCHEME

2 to state steps I n':~ilJ\..'Il:';C

or wrong response1

o 7

R

17