Spm Percubaan 2008 Kedah Chemistry Paper 2

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Chemistry Paper 2

Sepuoos Z%jam

,No.Karl Pengenalan:

Angka Giliran:

.

Nama :

Tingkatan:

.

PERSIDANGAN KEBANGSAAN PENGETUA-PENGETUA SEKOLAH MENENGAH NEGERI KEDAR DARUL AMAN

PEPERIKSAAN PERCUBAAN SPM 2008 CHEMISTRY

Paper 2

Two hours and thirty minutes

JANGAN BUKA KERTAS SOALAN INI SEHINGGA DIBERITAHU I. Kertassoalan in; adalah dalam dwibahasa.

2. Soalan dalam Bahasa Inggeris mendahului soalanyang sepadan dalam Bahasa Melayu.

Untuk Kegunaan Pemeriksa Markah Markah Bahagian Soalan Penuh Diperoleh I 2 3

3. Colondibenarkan menjawab keseluruhan atau sebahagian soalan sama ada dalam BahasaInggerisatau Bahasa Melayu.

A

4 5

6 7

4. Calondikehendaki membaca

8

maklumat di halaman belakang kertas

soalan ini.

B C

9 10 11

12

Jumlah Kertas soalan ini mengandungi 20 halaman bercetak

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Section A

[60 marks]

Answer all questions (Jawabsemua soalan)

1. Diagram 1 shows the apparatus set-up for the neutralisation reaction between a strong acid and a strong alkali. . Rajah J menunjukkan susunan radas untuk tindak balaspeneutralan amara satu asid kuat don satu alkali kuat.

Hydrochloric acid, 0.1 mol dm" Asid hidroklorik; 0.1 mol dm-J

25 em3 sodium hydroxide solution + phenolphthalein 25 c~ larutan natrium hidroksida +

C=:=~~--fenolftaJein DIAGRAM 1

3 25.0 em of sodium hydroxide solution is poured into a conical flask. A few drops of phenolphthalein are added into the solution. The solution in the conical flask is titrated with 0.1 mol dm,3 hydrochloric acid.

25.0 eM' lanaan natrium hidroksida dimasukkan Ire dalam sebuah kelalang Icon. Beberapa tlttkfenolftalein ditambah Ire daJam larutan itu. Larutan dalam kelalang Icon dititratkan dengan O. J mol dm-J asid hidroklorik: Hydrochloric acid is a strong acid. What is meant by a strong acid?

Asid hidroklorik adalah asid kuat. Apakah yang dimaksudkan dengan asid k:uaJ?

[2 marb] (b) Suggest an apparatus that can be used to measure 25.0 em J of sodium

hydroxide solution accurately.

Cadangkan satu radas yang dapat digunakan untuk menyukat 25.0 cmJ larutan natrium hidroksida dengan tepat.

[1 mark]

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(c)

State the colour change of the solution in the conical flask at the end point. Nyatakan perubahan warna larutan dalam kelalang leonpada takat akhir.

[1 mark] (d) (i)

Write a chemical equation for the above reaction. Tulis persamaan kimia bagi tindak balas di atas.

[1 mark] (ii)

In this experiment, 20.0 cm3 hydrochloric acid is needed to neutralise 25.0 cm 3 of sodium hydroxide solution. Calculate the molarity of the sodium hydroxide solution. Dalam eksperimen ini, 20.0 cm 3 asid hidroklorik diperlukan untuk meneutralkan 25.0 cm 3 larutan natrium hidroksida. Hitungkan kemolaran lanaan natrium hidroksida itu.

[2 markr] (e) (i)

The experiment is repeated with 0.1 mol dm' sulphuric acid to replace hydrochloric acid. Predict the volume of sulphuric acid needed to neutralise 25.0 cm3 sodium hydroxide solution. Eksperimen itu diulang dengan menggunakan O. J mol dm'3 asid sulfurik bag; menggantikan asid hidroklorik: Ramalkan isipadu asid sulfunk yang diperlukan untuk meneutralkan 25.0 cm 3 larutan natrium hidroksida.

[1 mark] (ii) Explain your answer in (e) (i). Terangkan jawapan anda dalam (e)(i).

[2 marks]

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2. Diagram 2 shows the apparatus set-up to determine the empirical formula of oxide metal M. Rajah 2 menunjukkan susunan radas untuk menentukan formula empirik bagi oksido logam M M oxide

OlcsidaM

-Gni",.."" Combustion tube

heat

Asbestos paper

Tiub pembakaran

panaskan

Kertas asbestos

DIAGRAM 2 (a)

(i)

Name two chemicals used to prepare hydrogen gas in the laboratory.

Namakan dua bahanyang digunakan untuk menyediakan gas hidrogen dalam makmal. [2 marks] (ii)

Write a chemical equation for the reaction in (a)(i).

Tuliskan persamaan kimia bagi tindak balas di (a)(;). [1 mark]

(b) Table 2 shows the result of the experiment: Jadual 2 menunjukkan keputusan eksperimen itu: Mass of combustion tube + asbestos paper

Jistm tiub pembakaran + kertas asbestos

39.25 g

Mass of combustion tube + asbestos paper + M oxide before heating

Jisim tiub pembakaran + kertas asbestos + oksida M sebelum pembakaran Mass of combustion tube + asbestos paper + product after heating Jisim tiub pembakaran + kertas asbestos + hasil selepas pembakaran [Relative atomic mass of 0=16. M=55] (i)

47.95 g 44.75g

Determine the empirical formula of M oxide.

Tentukan formula empirik bagi oksida M

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(ii) Write 8 chemical equation for the reduction of M oxide by hydrogen gas. Tulis persamaan kimia bagi penurunan oksida M oleh gas hidrogen.

[1 mark] (c) State one precaution that must be taken when carrying out the experiment. Nyatakan satu langkah berjaga-jaga yang mesti diambil semasa menjalankan eksperimen itu.

[1 mark] (d) Can the empirical formula of magnesium oxide be determined by the same method? Explain your answer. Bolehkah formula empirik bagi magnesium oksida ditentukan dengan kaedah yang

sama? Terangkanjawapan anda.

[2marb]

3. Polymers are long chained molecules made by joining together thousands of smaller molecules called monomers . Polimer adalah molekul berantai panjang yang terhasil daripada cantuman beribu-ribu molekul kecil yang dipanggil monomer.

(a) Polypropene and polyvinyl chloride are examples of polymers. State the name of their monomers. Polipropena dan polivinil klorida adalah contoh polimer. Nyatakan nama

monomer mereta. Polypropene: Polipropena

.

Polyvinyl chloride: Polivinil klorida

..

[2 marks]

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(b) Plastic bag used in our daily life is a type of synthetic polymer. State ODe advantage and one disadvantage of plastic bag. Beg plastik yang digunakan dalam kehidupan seharian ialah sejenis poJimer sintetik: Nyatakan satu kebaikan dan satu keburukan beg plastik: Advantage:

Kebaikan:

Disadvantage:

Keburukan: [2 marks] (c) Bronze is an alloy formed from copper and tin. Gangsa adalan suatu aloi yang terbentuk daripada kuprum dan timah. (i)

State one aim of alloying. Nyatakan satu tujuan pengaloian.

[1 mark] (ii)

State one use of bronze.

Nyatakan satu kegunaan gangsa. [1 mark] (iii)

Draw the arrangement of particles in bronze.

Lukiskan susunan zarah-zarah dalam gangsa.

[1 mark] (iv)

Bronze is harder than copper. Explain why.

Gangsa adalah lebih keras daripada kuprum. Terangkan mengapa.

[3 marks]

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4. Table 4 shows the proton number of two elements X and Y. Jadual 4 menunjukkan nombor proton bagi unsur X dan Y. Element X Y

Proton number 6 11 TABLE 4

(a)

Draw the atomic structure of atom X. Lukis struktur atom bagi atom X

[J mark] (b)

(i) \. Atom of element X has isotopes. What is meant by isotopes? Atom unsur X mempunyai isotop. Apakah yang dimaksudkan dengan

isotop?

[1 mark] (ii)

State one example of an isotope. Nyatakan satu contoh isotop.

[1 mark] (c)

(i)

Atom of element Y has a nucleon number of23. Calculate the number of neutrons in atom Y. Atom unsur Y mempunyai nombor nukleon 23. Hitungkan bi/angan neutron bagi atom Y.

[1 mark] (ii)

Write the standard representation of atom Y. Tuliskan simbol atom Y.

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(d) Methanol is an organic compound with melting point of -97 DC and boiling point of 6S DC. ' Etanol ialah satu sebatianorganikdengantakat lebur - 97 DC dan talcat didih 65 DC. (i)

What is the physical state of methanol at room temperature?

Apakah keadaan fizik bag; metanolpada suhu bilik? [1 mark]

(ii)

Draw the arrangement ofparticles of methanol at 100 DC.

Lukiskan susunanzarah metanolpada 100 DC.

[1 mark] (iii) State how the movement of methanol particles changes when heated

from room temperature to 100 DC.

Nyatakan bagaimana pergerakanzarah-zarah metanol berubahapablla dipanaskandari suhu bilik Ire 100 "c. [1 mark] (iv) Sketch the graph of temperature against time when methanol is heated from room temperature to 100 DC.

Lakarkan grafsuhu melawanmasa apabilametanoldipanaskan daripada suhu bilik Ire 100°C. Temperature! °c Suhul"C

Time/min Malcalmin

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5. An experiment is conducted to determine the rate of reaction between 25 em) of hydrochloric acid 0.1 mol dm" and 10.0 g of marble chips. The gas evolved is collected into a burette by water displacement technique. Diagram 5 shows the incomplete apparatus set-up for this experiment. Table 5 shows the result of the experiment. Satu eksperimen telah dijalankan untuk menentukan kadar tindak balas antara 25 em 3 asid hidroklorik 0.1 mol dm-) dan 10.0 g ketulan kalsium karbonat. Gas yang terbebas dikumpulkan ke dalam sebuah buret menggunakan kaedah sesaran air. Rajah 5 menunjukkan susunan radas yang tidak lengkap yang digunakan dalam eksperimen itu. Jadual 5 menunjukkan keputusan eksperimen itu.

Time/s Masals

Volume of gas/em' Isipadu f!as/cm

3

0

25

50

75

100

125

150

175

0

16

32

48

58

60

60

60

TABLE 5 [Relative atomic mass: Ca=40; C=12; 0=16. Molar volume of gas = 24 dnr' mol" at room condition]

Burrette Buret

Water

Hydrochloric acid Asid hidroklorik

Air

Marble chips Ketulan marmar

DIAGRAM 5 (a) Complete the diagram above with a suitable apparatus. Lengkapkan gambarajah di atas dengan radas yang sesuai.

[1 mark] (b) Write the chemical equation for the reaction between hydrochloric acid and calcium carbonate. Tuliskan persamaan kimia bagi tindak balas antara asid hidrokIorik dengan kalsium karbonat.

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Calculate the average rate of reaction in the first 50 seconds. Hitungkan kadar tindak balas purata dalam 50 saat yang pertama.

[1 mark]

(d)

(i)

Plot a graph of volume of gas against time on the graph paper provided. Lukiskan grajisipadu gas melawan masa menggunakan kertas grajyang dibekalkan. [4marb]

(ii)

Calculate the rate of reaction at 100 seconds. Hitungkan kadar tindak balas pada 100 saat .

[3 marks]

Graph of volume of gas against time 4541/2

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Graph of volume of gas against time

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6. Diagram 6 shows the flow chart of a series of conversion of carbon compounds.

Rajah 6 menunjukkan carta a/ir bagi suatu sir;penukaran sebatian karbon.

I

I Etana &bane I .,.--

fl

,.

Ethene

Etena

.

Ethanol

Etanol

IV Oxidation

Ethyl etanoate etil etanoat

V

SubstanceQ Bahan Q

CH3COOC2HS DIAGRAM 6 Based on Diagram 6 answer the following questions:

Berdasarkan Rajah 6. jawab soalan-soalan berikut:

(a)

Name the reaction in conversion I. Namakan tindak balas dalam perubahan J.

[1 mark} (b)

Ethanol is produced by hydration of ethene in II.

Etanol dihasilkan melalui penghidratan elena di /1 (i)

State the catalyst used in this reaction.

Nyatakan mangkinyang digunakan dalam tindak balas ini.

[1 mark} (ii)

Write a chemical equation for the reaction in II.

Tuliskanpersamaan kimia bagi tindak balas di /1 [1 mark}

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(iii)

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Name the reaction that converts glucose to ethanol in the laboratory. Namakan tindak balas yang menukarkanglukosa kepada etanol di dalam makmal.

[1 mark] (c)

(i)

Name substance Q. Namakan bahan Q. [1 mark]

(ii)

Suggest an oxidising agent that can be used in reaction IV. Cadangkan satu agen pengoksidaan yang dapat digunakan dalam tindale balas IV.

[1 mark] (d)

Write a chemical equation for the reaction in III. Tuliskan persamaan Idmiauntuk tindakbalas di III

[1 mark]

(e)

Ethanol and substance Q react to produce substance X with a molecular formula of CH3COOC2Hs. Etanol dan bahan Q bertindak balas untuk menghasilkan bahan X dengan formula molelcul CHJCOOC2H,. (i)

Name the reaction in V to produce substance X. Namakan tindak balas di V untuk menghasilkanbahan X

[1 mark]

(ii)

State one physical property of substance X. Nyatakan satu sifat fizik bahan X

[1 mark]

(iii) Draw the structural formula of substance X. Lukiskan formula struktur untuk bahan X

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SectionB [20 marks]

Answer anyone question. (Jawab mana-mana satu soalan) 7. (a)

Dilute ethanoic acid (vinegar) is electrolysed using carbon electrodes. What is produced at the cathode? Write a half-equation for the reaction.

Elekirolists asid etanoik cair telah dijalankan menggunakan elelctrod ­ elelctrod karbon. Apakah yang terhasil di katod. Tuliskan setengahpersamaan bagi tindak balas tersebut. [2 markJ] (b) Diagram 7 shows two types of cells. Rajah 7 menunjukkanduajenis sel.

v

----

MagnesiumMagnesium chloride solution

....,r--~

Copper

t

. -'-':=" .- "ill:..: :~..­. "-

-

"

­

Copper

Copper(ll) Copper(II) oitrate solution

CellA

nitrate

-­

--­-- --

solution

Cell B

DIAGRAM 7 Compare and contrast cell A and cell B. Include in your answer the observations and half equations for the reactions at the electrodes in both cells.

Banding dan bezakan sel A dan sel B. Sertakandalamjawapan anda pemerhatian dan setengahpersamaan bagi tindakbalasdl eleksrod-eleksrod kedua-dua sel.

[8 markJ] (c)

A student intends to electroplate an iron ring with silver.

Seorang pelajar ingin menyadurcincin besi dengan argentum. (i)

State two purposes of electroplating the iron ring.

Nyatakan dua tujuan menyadurcincin besi tersebut. [2 marks]

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(ii)'

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Design a laboratory experiment to electroplate the iron ring.

Rancangkan satu eksperimenmakmaluntuk menyadurcincin besi tersebut. Your answer should consist of the following • Procedures of the experiment. • A labelled diagram showing the set up of apparatus. Half equations for the reactions at both electrodes. • • Observations at both electrodes. Jawapan anda hendaldah termasukperkara-perkaraberikut:

• • • •

Langkah-langkah eksperimen: Gamber rajah susunanradas berlabel. Selengah persamaan bagi lindale bolas di kedua-duaelektrod: Pemerhatian di kedua-dua elektrod. [8 marks]

8. Figure 8 shows the electron arrangement for atoms P, Q and R. Rajah8 menunjulclcan susunan elektron bagi atom-atom P. Q dan R.

AtomQ

AtomP

AtomR

Based on figure 8. answer the following questions:

Berdasarkanrajah 8. jawab soalan-soalan berikut:

(8) (i) State the location of atom R in the Periodic Table of Elements.

Nyalalran kedudukan atom R dalam Jadual Berkala Unsur. (ii)

Explain how you determine the group and the period of atom R.

Terangkanbagaimanaanda menentukan kumpulandon kala bagi atom

R. [S marks] (b) Atoms P and Q can form chemical bonds with atom R.

Atom P don Q boleh membentukikaran kimia dengan atom R. State the type ofchemical bond and explain how the bond is formed between: Nyatakanjenis lkatan kimia don terangkan bagaimana ilratan terbentuk antara:

(i) (ii)

Atoms P and R Atoms Q and R [11 marks]

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(c) State one physical property of the compound formed in (b) (i) and the compound formed in (b) (ii), Explain the differences in the physical property stated.

Nyatakan sam sifat fizik bagi sebatianyang terbentulc di (b)(i) dan bagl sebatian yang terbemuk di (b)(ii). Terangkan perbezaan bagl sifatfizilcyang dinyatakan: [4marb]

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Section C [20 marks] Answer anyone question. (Jawab mana-manasatu soalan) 9.

(a)

An oxidising agent in a reaction can also become a reducing agent in another reaction. Discuss this statement based on the reactions represented by the following equations : Satu agen pengoksidaan dalam suatu tindak balas boleh juga menjadi agen penurunan dalam tindak balas yang lain. Bincangkanpemyataan ini berdasarkan tindak balas yang ditunjukkandalam persamaan berikut: i) 2Fe 2+(aq) + Br2(aq) -+ 2Fe3+(aq) + 2Br-(aq) ii) Fe 2+ (aq) + Zn(s) -+ Fe(s) + Zn 2+ (aq) [4 marks]

(b)

Displacement reaction between magnesium and copper(II) sulphate solution can also be classified as a redox reaction. With the aid of half­ equations, explain the above statement in terms of change in oxidation number. Tindak balas penyesaran antara magnesiumdan larutan leuprum(/I) sulfat bolehjuga dikelaskan sebagai satu tindak balas redoks. Dengan bantuan setengah persamaan,jelaskan pernyataan di atas dari segi perubahan dalam nombor pengoksidaan: [4 marks]

(c)

(i)

State the meaning of oxidation and reduction in terms ofelectron transfer. Nyatakan maksud pengo/csidaan dan penurunan dari segi pemindahon elektron. [2marh]

(ii) A student intends to investigate the redox reaction on the transfer of electrons at a distance. Diagram 9 shows the set up of apparatus used by the student. Seorang pelajar ingin menyiasat tentang tindak bolas redoks melalui pemindahan elektron pada satu jaraJc. Rajah 9 menunjulrkan SUSU1Ul1I radas yang telah digunakan oleh pelajar tersebta.

Carbon electrode Negative terminal

Carbon electrode Positive terminal

Iron(lI)sulphate

solution

Lannan jerum(II) sulfat

. Bromine water : Air bromin Dilute sulphuric acid Asid sulfurik cair

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Describe the oxidation and reduction processes in tenus of electron transfer that occur at the negative and positive terminals. Write the half equation for the reaction that takes place at each terminal. State the changes that can be observed after 10 minutes. Terangkan proses pengoksidaan dan penurunan yang berlaku di terminal negatifdan terminal positifdari segi pemindahan elekiron. Tuliskan setengah persamaan bagi tindak balas yang berlaku di setiap terminal. Nyatalean perubahan yang dapat diperhatikan selepas 10 minit.

[10 marks]

10 (a)

What is meant by exothermic and endothermic reaction? Explain the changes in the energy content of the reactants and products for both the reactions. Apakah yang dimaksudkan dengan tindak balas eksotermik dan endotermik? Huraikan perubahan kandungan tenaga bahan tindak balas dan hasil tindak balas bagi kedua-dua tindak balas tesebut? [4 marks]

(b)

Figure 10 represents an energy level diagram for a chemical reaction. Rajah 10 mewakili gambar rajah aras tenaga bagi satu tindak balas kimia. Energy tenaga

A+B l\H

= -X kJ mol" C+D

FIGURE 10 State four information that can be obtained from the energy level diagram. Nyatakan empat maklumat yang dapat diperolehi daripada gambar rajah aras tenaga itu.

[4 marks]

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(c) Describe an experiment to determine the heat of combustion of ethanol. Your explanation should include the following: Terangkan sam eksperimen untukmenentukan habapembakaranetanol. Penerangan anda perlu mengandungi perkara berikut: •

•

procedure of experiment prosedu1' eksperimen result and calculations lreputusan dan pengiraan [ 12 marks]

END OF QUESTION PAPER KERTAS SOALAN TAMAT

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PEPERIKSAAN PERCUBAAN SPM 2008 NEGERI KEDAH DARUL AMAN MARKING SCHEME CHEMISTRY PAPER 2 Section A 1.

(a)

An acid that dissociates/ ionises completely in water to form a high concentration of hydrogen ions pipette From pink to colourless (i) HCl + NaOH Æ NaCl + H2O (ii) 0.1 x 20 = 1 Mb x 25 1

(b) (c) (d)

(e)

1 1 1 1 1 1

25 Mb = 2 Mb = 0.08 mol dm-3 10 cm3 // half the volume of hydrochloric acid Sulphuric acid is a diprotic acid whereas hydrochloric acid is a monoprotic acid. So, the sulphuric acid used has twice the number of hydrogen ions compared to hydrochloric acid .

(i) (ii)

Total

2.

(a)

(i)

(b)

(ii) (i)

1 1 1 1

10

Zinc hydrochloric acid / suphuric acid Zn + 2HCl Æ ZnCl2 + H2

1 1 1 1

1 1

Empirical formula is MO2

( c)

(d)

(ii) MO2 + 2H2 Æ M + 2H2O The air in the combustion tube must be displaced before lighting the hydrogen gas// The heating, cooling and weighing is repeated until a constant mass is obtained

1 1

No. Magnesium is more reactive than hydrogen.

1 1 Total

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(a)

Propene Vinyl chloride // Chloroethene

1 1

(b)

Advantage: Light // Cheap // convenient

1

(c)

Disadvantage: Non-biodegradable // produces toxic gas when burnt i Increase hardness // reduce corrosion / rusting // improve the appearance//to make it more attractive

1 1

ii

1

To make Medals // swords // statues // bells

iii

1

Copper Tin

iv

Atoms/particles in copper are arranged in an orderly manner in layers. The presence of tin atoms disturbs the orderly arrangement of copper atoms. This will make it difficult for the layers of tin atoms to slide on each other. Total

4

1

1 1 10

1

(a)

X

(b)

(c)

i

Isotopes are atoms (of the same element) with the same number of protons/proton number but different number of neutrons/nucleon number.

1

ii

Any example of isotope

1

i

Sample answer; carbon-14,cobalt-60, sodium-24 etc 12

1

ii

23

1

Y

11

(d)

i

Liquid

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(ii)

iii

Becomes faster/ more active

iv o

Temperature / C

1 correct curve boiling point

1 1

65

Time / min Total 5

10

(a)

1

The stopper is drawn in the correct position(half in, half out) refer the diagram (b) (c)

(d)

2HCl + CaCO3 Æ CaCl2 + H2O + CO2 3 32 cm 50 s = 0.64 cm3s-1 (i) Both axes are labelled with the correct units scales are suitable(cover ½ graph paper) All points are transferred correctly Smooth curve

1 1

(ii)

1 1 1

1 1 1 1

A tangent is drawn on the graph Calculation 0.246 cm3s-1 + 0.024 // range [0.222 - 0.270]

Total

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(a) (b)

(c)

(d) (e)

Hydrogenation// addition (of hydrogen) (i) Phosphoric acid // H3PO4

1 1

C2H4 + H2O Æ C2H5OH Fermentation Ethanoic acid Acidified potassium dichromate(VI) solution // Acidified potassium manganate(VII) solution C2H5OH Æ C2H4 + H2O (i) Esterification

1 1 1 1

(ii)

1

(ii) (iii) (i) (ii)

- has a sweet smell// fruity smell - a neutral compound - colourless liquid - slightly soluble in water - readily soluble in organic compounds [ Choose any one ]

1 1

1

(iii) H

O

H H

H–C–C–O –C–C–H H

H H Total

SMS MUZAFFAR SYAH , MELAKA

10

MOZ@C j2k

Section B 7

(a) (b)

Hydrogen(gas) 2H+(aq) + 2e Æ H2(g) Properties 1. Type of cell 2. Energy change 3. Electrodes

4. Ions in electrolyte 5. Half equation

6. Observation

1 1 Cell A Voltaic cell Chemical Æ electrical Positive terminal: Copper Negative terminal: Magnesium Cu2+, SO42-, H+ and OHions Positive terminal: Cu2+ + 2e Æ Cu Negative terminal Mg Æ Mg2+ + 2e Positive terminal: Copper plate becomes thicker Magnesium becomes thinner/dissolve

(c)

(i) (ii)

Cell B Electrolytic cell Electrical Æ chemical Anode: Copper Cathode: Copper

2

1 1 1

Cu2+, SO42-, H+ and OHions Anode: Cu Æ Cu2+ + 2e Cathode: Cu2+ + 2e Æ Cu Anode: Copper dissolves//become thinner Cathode: Copper becomes thicker

Improve the appearance//to make it more attractive To prevent/ reduce corrosion/ rusting Procedure: 1. Iron ring is then connected to the negative plate on the battery while the silver plate is connected to the positive terminal of the battery//Iron ring is made as cathode while silver plate is made as anode 2. Both plates are immersed into the silver nitrate solution. 3. The circuit is completed

1 1 1 1

1

8

1 1

2

1

1 1

Functio nal apparatus set-up Label correctly: silver plate Silver nitrate solution Iron ring Cathode: Ag+ + e Æ Ag Observation: Grey /silvery solid is deposited Anode : Ag Æ Ag+ + e Observation: Anode/silver become thinner//dissolve

1 1

1 1 1 1 Total

SMS MUZAFFAR SYAH , MELAKA

max 8/9 20

MOZ@C j2k

8

(a)

(b)

(i)

Atom R is located in Group 17, Period 3

(ii)

Electron arrangement of atom R is 2.8.7. It is located in Group 17 because it has seven valence electron. It is in Period 3 because it has three shells filled with electron Atoms P and R form covalent bond. To achieve the stable electron arrangement, atom P needs 4 electrons while atom R needs one electron. Thus, atom P shares 4 pairs of electrons with 4 atoms of R, forming a molecule with the formula PR4 // diagram

(i)

1 1 1 1 1

5

1 1 1 1 1

R

R

P

R

R

(ii)

Atom Q and atom R form ionic bond. Atom Q has the electron arrangement 2.8.1. and atom R has the electron arrangement 2.8.7. To achieve a stable (octet )electron arrangement, atom Q donates 1 electron to form a positive ion// equation Q Q+ + e

1

Atom R receives an electron to form ion R-//equation and achieve a stable octet electron arrangement. R+e R-

1 1

Ion Q+ and ion R- are pulled together by the strong electrostatic forces to form a compound with the formula QR// diagram

1

1 1

+ Q

R

11

SMS MUZAFFAR SYAH , MELAKA

MOZ@C j2k

(c)

1 1

The ionic compound/ (b)(ii) dissolves in water while the covalent compound / (b)(i)does not dissolve in water. Water is a polar solvent that can cause the ionic compound to dissociate into ions. Covalent compounds are non-polar and can only dissolve in organic solvents.

1 4

1

OR The melting point of the ionic compound/ (b)(ii) is higher than that of the covalent compound/ (b)(i) . This is because in ionic compounds ions are held by strong electrostatic forces. High energy is needed to overcome these forces. In covalent compounds, molecules are held by weak intermolecular forces. Only a little energy is required to overcome the attractive forces.

1 1 1 max 4/5

1 1

OR The ionic compound/(b)(ii) conducts electricity in the molten or aqueous state whereas the covalent compound/(b)(i) does not conduct electricity. This is because in the molten or aqueous state, ionic compounds consist of freely moving ions. Covalent compounds are made up of molecules only

1 1 1 4 20

1 Total

9

(a)

(i)

(ii)

(b)

Based on the equation, iron(II) ion is oxidised to iron(III) ion So, iron(II) ion acts as a reducing agent Based on the equation, iron(II) ion is reduced to iron So, iron(II) ion acts as an oxidising agent

1

Mg → Mg 2 + + 2e

1

Oxidation number of magnesium increases from 0 to +2, So magnesium undergoes oxidation

1

Cu 2 + + 2e → Cu

1

oxidation number of copper decreases from +2 to 0, so copper(II) ion undergoes reduction (c)

1 1 1

(i)

Reduction is a reaction that involves gain of electron. Oxidation is a reaction that involves loss of electron.

SMS MUZAFFAR SYAH , MELAKA

4

1

4

1 1

2

MOZ@C j2k

(ii) At the negative terminal: Iron(II) ion releases one / loses one electron and is oxidised to iron(III) ion. Fe2+ Æ Fe3+ + e The green coloured solution of iron(II) sulphate turns brown. The electron flows from the negative terminal// carbon immersed in iron(II) sulphate solution to the positive terminal// carbon immersed in bromine water.

1 1 1 1 1

At the positive terminal: Bromine accepts electron and is reduced to bromide ions, BrBr2 + 2e Æ 2BrThe brown coloured bromine water turns colourless. The deflection of the galvanometer needle shows that there is a flow of current

1 1 1 1 1

10

Total 20 10

(a)

(b)

Exothermic reaction is a reaction that releases heat to the surrounding The energy content of the products is lower than the energy content of the reactants Endothermic reaction is a reaction that absorbs heat from the surrounding The energy content of the products is higher than the energy content of the reactants

1

1

4

A reacts with B to form C and D A and B are the reactants while C and D are the products Heat energy is released //The reaction is exothermic Total energy content of A and B/reactants is higher than total energy content of C and D/products

1 1 1 1

4

(c)

thermometer Copper container water

Spirit lamp + ethanol

SMS MUZAFFAR SYAH , MELAKA

1 1

MOZ@C j2k

250 cm3 of water is measured using a measuring cylinder and is then poured into a copper container. The copper container is placed on a tripod stand. The initial temperature of the water is measured and recorded. A spirit lamp containing ethanol is weighed and recorded. The spirit lamp is placed directly below the copper container(as in the diagram.) The wick of the spirit lamp is lighted. The water is stirred using a thermometer. When the increase in water temperature is 30 oC, the flame is put off and the highest temperature reached is recorded. The spirit lamp is weighed again. Results: Initial temperature of water = t1 oC Highest temperature of water = t2 oC Rise in temperature = (t2 - t1)oC = T oC Mass of lamp + ethanol before combustion = m1 g Mass of lamp + ethanol after combustion = m2 g Mass of ethanol burnt = (m2 – m1) g Number of mol of ethanol = (m2 – m1) 46

= n

q n x 1000

1 1 1 1 1 1 1 1

1

1 1

1

Heat change = 250 x 4.2 x T = qJ Heat of combustion = -

1

kJ mol-1

1 Max 12/14 Total 20

SMS MUZAFFAR SYAH , MELAKA