TOPIC 6 : ELECTROCHEMISTRY1 Which of the folllowing is an electrolyte?

Antara berikut, yang manakah elektrolit?

ABCD

GlucoseCopperNaphthaleneSodium chloride

2 Diagram 7 shows the set up of the apparatus for the electrolysis of molten lead(II) oxide.Rajah 7 menunjukkan susunan radas bagi elektrolisis leburan plumbum(II) oksida.

What are the products formed at the anode and the cathode?Apakah hasil yang terbentuk pada anod dan katod?

AnodeAnod

CathodeKatod

A LeadPlumbum

OxygenOksigen

B Oxygen Oksigen

LeadPlumbum

C HydrogenHidrogen

OxygenOksigen

D OxygenOksigen

HydrogenHidrogen

3. Copper (II) sulphate solution is electrolysed using copper electrodes. What can be observed at the anode and cathode after 30 minutes?Larutan kuprum(II) sulfat dielektrolisiskan menggunakan elektrod kuprum. Apakah yang diperhatikan pada anod dan katod selepas 30 minit?

Anode Cathode

A Copper plate becomes thinnerPlat kuprum menjadi nipis

Copper plate becomes thicker Plat kuprum menjadi tebal

B Copper plate becomes thinnerPlat kuprum menjadi nipis

Gas bubbles are releasedGelembung-gelembung gas terbebas

C Copper plate becomes thicker Plat kuprum menjadi tebal

Copper plate becomes thinnerPlat kuprum menjadi nipis

D Gas bubbles are releasedGelembung-gelembung gas terbebas

Copper plate becomes thicker Plat kuprum menjadi tebal

4. Table 2 shows the observation of electrolysis of a substance using carbon electrode .Jadual 2 menunjukkan pemerhatian bagi elektrolisis suatu bahan menggunakan elektrod

Diagram 7Rajah 7

Iron ring

Iron(II) sulphate solution

Copper

Iron(II) sulphate solution

Iron ring Copper

karbon.

ElectrodeElektrod

ObservationPemerhatian

AnodeAnod

A greenish-yellow gas releasedGas berwarna kuning kehijauan terbebas

CathodeKatod

A colorless gas which burns with a ‘pop’ sound is releasedGas yang tidak berwarna dan terbakar dengan bunyi pop terbebas

The electrolyte maybeElektrolit itu mungkin

ADilute hydrochloric acidAsid hidroklorik cair

BConcentrated potassium chloride solution.Larutan kalium klorida pekat

CCopper (II) chloride solution.Larutan kuprum (II) klorida

DConcentrated magnesium bromide solutionLarutan magnesium bromide pekat.

5 Which of the following set up of apparatus is correct to electroplate iron ring with copper? Antara susunan radas berikut, yang manakah betul untuk menyadur cincin besi dengan

kuprum?

A

B

C

Table 2Jadual 2

Iron ring

Copper(II) sulphate solution

Copper

Copper(II) sulphate solution

Iron ring Copper

D

6 The diagram shows the set up of the apparatus for the electrolysis of copper(II) nitrate solution.Rajah menunjukkan susunan radas bagi elektrolisis larutan kuprum(II) nitrat.

Which of the following is produced at copper electrode X?Antara berikut, yang manakah dihasilkan di elektrod kuprum X?

A CopperKuprum

B OxygenOksigen

C Hydrogen ionsIon hidrogen

D Copper(II) ionIon kuprum(II)

7 Diagram 7 shows the set-up of the apparatus of an electrolytic cell.Rajah 7 menunjukkan susunan radas bagi satu sel elektrolisis.

Carbon electrodes

Copper(II) sulphate solution

Which of the following half-equations represents the reaction that occurred at electrode P?Antara persamaan setengah berikut, yang manakah mewakili tindak balas yang berlaku di elektrod P?

ABCD

Na+ + e Na2H+ + 2e H2

2Cl- Cl2 + 2e4OH- O2 + 2H2O + 4e

8 Which of the following is the cation in molten lead(II) bromide?

A H+

B Pb2+

C Br -

D OH-

9 Diagram 1 shows the set up of the apparatus for the electrolysis of copper(II) sulphate solution.

DIAGRAM 1

Which of the following is formed at the anode?A OxygenB CopperC SulphurD Hydrogen

10 Impure copper can be purified by using electrolysis. Which of the following pair of electrodes is correct?

Diagram 7

Kuprum tak tulen boleh ditulenkan dengan menggunakan elektrolisis. Antara pasangan elektrod berikut, yang manakah betul?

A

B

C

D

AnodeAnod

CathodeKatod

Pure copperKuprum tulen

Impure copperKuprum tak tulen

Impure copperKuprum tak tulen

Pure copperKuprum tulen

CarbonKarbon

Pure carbonKarbon tulen

CarbonKarbon

Impure carbonKarbon tak tulen

11 Table 4 shows information about three simple voltaic cell.Jadual 4 menunjukkan maklumat tentang tiga sel ringkas.

Voltaic cell Electrodes used Voltage (V)P Iron and Zinc 0.2Q Zinc and magnesium 1.6R Copper and magnesium 2.6

What is the potential difference of the voltaic cell which consists of copper and iron electrodes?Apakah nilai voltan bagi sel yang mengandungi elektrod kuprum dan ferum ?

A 0.4B 0.6C 0.8D 2.4

12 Table 3 shows the result of an experiment for three simple voltaic cells.Jadual 3 menunjukkan keputusan suatu eksperimen bagi tiga sel ringkas.

Positive terminal Negative terminal Voltage (V)W X 0.3Y X 0.8X Z 1.9

The arrangement of the metals in the electrochemical series in descending order of electropositivity isSusunan logam-logam mengikut keelektropositifan dalam siri elektrokimia mengikut urutan menurun adalah

Table 4Jadual 4

Table 3Jadual 3

Metal QMetal P

V

- +

A W, Z, X, YB Y, W, X, ZCD

Y, W, Z, X

Z, X, W, Y

Trial kedah 200913 .Diagram 16 shows the set up apparatus of a simple chemical cell.

Rajah 16 menunjukkan susunan radas bagi sel kimia ringkas.

Diagram 16 Rajah 16

What are metals P and Q?Apakah logam P dan Q?

Metal PLogam P

Metal Q Logam Q

A CopperKuprum

ZincZink

B LeadPlumbum

IronBesi

C MagnesiumMagnesium

IronBesi

D TinTimah

ZincZink

Trial kedah 2009

14 Diagram 1 shows the set-up of apparatus of a chemical cell.

e

Electrolyte

Rajah 1 menunjukkan susunan radas bagi sel kimia.

Diagram 1

Which of the following substances is most likely to be Y?Antara bahan berikut, yang manakah mungkin Y?

ABCD

IronMagnesiumSilverCopper

15 Diagram 5 shows an apparatus set-up for a chemical cell prepared by a student.Rajah 5 menunjukkan susunan radas bagi sel kimia yang disediakan oleh seorang pelajar.

The student wants to modify the chemical cell so that it produces a higher voltage. What modification should the student make?Pelajar tersebut ingin mengubahsuai sel kimia itu supaya voltan yang dihasilkan adalah lebih tinggi. Apakah pengubahsuaian yang perlu dilakukan oleh pelajar tersebut?

A

B

C

D

Use a wider metal plates

Gunakan kepingan logam yang lebih lebar

Substitute zinc with magnesium

Gantikan zink dengan magnesium

Reduce the distance between the two metal plates

Kurangkan jarak antara dua kepingan logam

Use magnesium sulphate solution as the electrolyte

Gunakan larutan magnesium sulfat sebagai elektrolit

Trial kedah 2009

Diagram 5

Electrode X

V

Electrode Y

Electrolyte

16 Diagram 5 shows the set up of apparatus of a simple voltaic cell.

DIAGRAM 5

Which of the following pairs of electrodes is correct if the electrons move from electrode X to electrode Y?Antara pasangan elektrod berikut,yang manakah benar jika elektron bergerak dari elektrod X ke elektrod Y?

Electrode X Electrode YA Tin AluminiumB Zinc MagnesiumC Lead IronD Copper Silver

`17 The table shows information about three simple chemical cells.Jadual menunjukkan maklumat tentang tiga sel kimia ringkas

Pair of metalsPasangan logam

Potential difference/VBeza upaya/V

Metal of negative terminal

Logam terminal negatifP and copperP dan kuprum 0.45 P

Q and copperQ dan kuprum 1.30 Q

R and copperR dan kuprum 0.56 Cu

Based on the information in the table, what is the potential difference of the pair of metals Q and R?Berdasarkan maklumat dalam jadual, apakah beza upaya antara pasangan logam Q dan R?

A

B

C

0.74

0.85

1.01

X Y

CarbonKarbon

D 1.86

18 Diagram 10 shows the set up of the apparatus of elecrolysis of 2.0 mol dm-3 potassium chloride solution. Rajah 10 menunjukkan susunan radas elektrolisis bagi larutan kalium klorida 2.0 mol dm-3.

Diagram 10 Rajah 10

What is the products at electrode X and electrode Y?Apakah hasil di elektrod X dan di elektrod Y?

X YA Chlorine

KlorinOxygenOksigen

B HydrogenHidrogen

ChlorineKlorin

C OxygenOksigen

HydrogenHidrogen

D HydrogenHidrogen

Carbon dioxideKarbon dioksida

19 The diagram shows the set up of the apparatus of a simple chemical cell.Rajah menunjukkan susunan radas bagi sel kimia ringkas.

Which of the following is metal X?

2.0 mol dm-3 potassium chloride solutionLarutan kalium klorida 2.0 mol dm-3

Antara berikut, yang manakah logam X?

A ZincZink

B LeadPlumbum

C MagnesiumMagnesium

D AluminiumAluminium

20 The diagram shows four simple chemical cells. In each cell zinc is used as one of the electrodes.Rajah menunjukkan empat sel kimia ringkas. Dalam setiap sel, zink dijadikan salah satu elektrod.

In which cell does zinc act as the positive terminal?Di sel manakah zink bertindak sebagai terminal positif?

A Cell SSel S

B Cell RSel R

C Cell P

Sel P

D Cell QSel Q

21 Table 7 shows the potential difference of three simple voltaic cells.Jadual 7 menunjukkan beza upaya bagi tiga sel ringkas.

CellSel

Pair of metalPasangan logam

Potential difference Beza upaya (V)

Negative terminalTerminal negatif

I Mg and Cu 3.0 Mg

II Mg and Zn 1.5 Mg

III Zn and Fe 0.5 Zn

Table 7Jadual 7

What is the potential difference of a simple voltaic cell for pair of iron and copper?Berapakah beza upaya dari sel voltan mudah bagi pasangan logam besi dan kuprum

A

B

C

D

0.5 V

1.0 V

1.5 V

2.5 V

22 What are the products formed at the anode when molten sodium chloride and 0.001mol dm-3 aqueous sodium chloride are electrolysed separately, using graphite electrodes? Apakah hasil yang terbentuk di anod apabila natrium klorida lebur dan 0.001 mol dm -3 larutan natrium klorida dielektrolisiskan, dengan menggunakan elektrod grafit?

Product at anode for molten NaClHasil di anod untuk leburan NaCl

Product at anode for 0.001 mol dm-3 aqueous NaClHasil di anod untuk larutan akues NaCl 0.001 mol dm-3

AChlorine Klorin

ChlorineKlorin

BChlorine Klorin

Oxygen Oksigen

COxygen Oksigen

ChlorineKlorin

DOxygenOksigen

OxygenOksigen

23 Which of the following combinations should be used to electroplate an iron spoon with nickel?Antara gabungan berikut,manakah yang patut digunakan untuk menyadur sebatang sudu besi dengan nikel?

CathodeKatod

AnodeAnod

ElectrolyteElektrolit

A Iron SpoonSudu besi

Nickel rodRod nikel

Nickel nitrate solutionLarutan nikel nitrat

B Nickel rodRod nikel

Iron SpoonSudu besi

Nickel nitrate solutionLarutan nikel nitrat

C Iron SpoonSudu besi

Nickel rodRod nikel

Iron (II) sulphate solutionLarutan ferum(II) sulfat

D Iron SpoonSudu besi

Nickel rodRod nikel

Dilute sulphuric acidAsid sulfurik cair

24 The figure shows a simple chemical cell.Gambarajah menunjukkan sebuah sel kimia ringkas.

Which pair of metals will produce an electron flow, in the direction shown? Pasangan logam manakah akan menghasilkan arah pergerakan elektron yang ditunjukkan?

Metal PLogam P

Metal RLogam R

AMagnesiumMagnesium

CopperKuprum

BCopperKuprum

LeadPlumbum

CTinTimah

IronFerum

DIronFerum

AluminiumAluminium

25 Which of the following diagram shows the metal displacement reaction will be occurred ? Antara rajah berikut yang manakah menunjukkan tindak balas penyesaran logam akan berlaku?

P Q

e

CopperKuprumCopper(II) nitrate solutionLarutan kuprum(II) nitrat

Metal MLogam MSolution YLarutan Y

A

B

C

D

26 Diagram 6 shows the set- up of the apparatus of a chemical cell. The arrow shows the direction of the electrons flow.Rajah 6 menunjukkan susunan radas satu sel kimia.Anak panah menunjukkan arah pengaliran elektron.

CopperKuprum

Silver nitrateArgentum nitrat

LeadPlumbum

Iron(II) chlorideFerum(II)

Zinc Zink

Sodium sulphateNatrium sulfat

CopperKuprum

Zinc sulphateZink sulfat

Diagram 6 Rajah 6

What are metal M and solution Y?Apakah logam M dan larutan Y?

Metal M

Logam M

Solution Y

Larutan Y

A Silver

Argentum

Silver nitrate

Argentum nitrat

B Lead

Plumbum

Lead(II) nitrate

Plumbum(II) nitrat

C Zinc

Zink

Zinc(II) nitrate

Zink(II) nitrat

D Magnesium

Magnesium

Magnesium nitrate

Magnesium nitrat

27 The table below shows the results of an experiment involving 3 voltaic cells, using different pairs of metals as electrodes.Jadual di bawah menunjukkan keputusan eksperimen ke atas 3 sel voltan, yang menggunakan pasangan logam yang berbeza.

What is the voltage produced by a cell using iron and copper as electrodes?Apakah nilai voltan yang terhasil dalam sel yang menggunakan elektrod ferum dan kuprum?

A 0.8B 1.1C 1.4D 3.1

Voltaic CellSel Voltan

ElectrodesElektrod

Voltage/VVoltan / V

PMagnesium and copperMagnesium dan kuprum

2.8

QZinc and magnesiumZink dan magnesium

1.7

RIron and ZinkFerum dan zink

0.3

Potassium iodide solution

A

Carbon electrode X Carbon electrode Y

DIAGRAM 1

PAPER 2SECTION A

1 Diagram 1 shows the set up of the apparatus to investigate the electrolysis of 1.0 mol dm-3 potassium iodide solution.

a) i) What is meant by anion?

………………………………………………………………………………………………..

[1 mark]

ii) Which electrode is cathode ?

……………………………………………………………………………………………… [1 mark]

b) i) State all the ions present in potassium iodide solution.

………………………………………………………………………………………………..

[1 mark]

ii) State the ion that will be discharged at

Electrode X: ………………………………………………………..

Electrode Y: ………………………………………………………..

[2 marks]

(c) (i) What is the observation at electrode X?

……………………………………………………………………………………………….

[1 mark]

(ii) Write the half equation for the reaction at electrode X.

………………………………………………………………………………………………..

[1 mark]

(d) (i) Name the gas collected at electrode Y.

…..…………………………………………………………………………………………..

[1 mark]

(ii) The number of moles gas collected at electrode Y is 0.1 . Calculate the volume of the gas collected.

[1 mol of gas occupies a volume of 24.0 dm3 at room temperature and pressure]

Copper plate / Kepingan kuprum

Zinc sulphate solutionLautan zink sulfat

Zinc plate / Kepingan zink

Copper(II) sulphate solution Larutan kuprum(II) sulfat

Porous pot / Pasu berliang

[1 mark]

(e) If 0.0001 mol dm-3 potassium iodide solution is used as electrolyte

(i) What is produced at electrode X at the beginning of the experiment?

………………………………………………………………………………………

[1 mark]

(ii) Write the half equation in (e)(i)

………………………………………………………………………………………

[1 mark] 2. Diagram 3 shows part of the set up of apparatus of chemical cell.

Rajah 3 menunjukkan sebahagian daripada susunan radas bagi sel kimia.

(a) Draw a complete set-up of apparatus for chemical cell on Diagram 3.Lukiskan susunan radas yang lengkap bagi sel kimia dalam Rajah 3.

[1 mark][1 markah]

(b) Label the negative electrode as ( - ) and positive electrode as ( + ) on the completed chemical cell.Labelkan elektrod negatif sebagai ( - ) dan elektrod positif sebagai ( + ) pada rajah sel kimia yang telah lengkap.

[1 mark][1 markah]

(c) State the flow of electron for the chemical cell in diagram 3.Nyatakan arah pengaliran elektron bagi sel kimia pada Rajah 3.

Diagram 3Rajah 3

[1 mark][1 markah]

(d) What is the function of the porous pot used in the above chemical cell?Apakah fungsi pasu berliang yang digunakan dalam sel kimia di atas?

[1 mark]

(e) What can you observed at the negative electrode?Apakah yang boleh anda perhatikan pada elektrod negatif?

[1 mark][1 markah]

(f) Write half equation for the discharged of ions at positive electrode.Tuliskan persamaan setengah bagi ion yang didiscas pada elektrod positif.

[1 mark][1 markah]

(g) (i) If the copper plate in the chemical cell above is replaced by silver metal, what will happen to the voltage reading of the cell.Jika kepingan kuprum di dalam sel kimia di atas digantikan dengan logam argentum,apakah yang berlaku kepada nilai voltan yang akan terhasil.

[1 mark][1 markah]

(ii) Give the reasons for your answer.Berikan sebab bagi jawapan anda.

[1 mark][1 markah]

(h) Table 3 shows the voltage of chemical cell using metals A, B and C as the electrode Jadual 3 menunjukkan nilai voltan bagi sel kimia menggunakan logam A, B dan C sebagai elektrod.

Table 3Jadual 3

Based on the information given, calculate the voltage of a chemical cell using metal A and B as the electrodes.

Pairs of metalPasangan logam

Voltage (V)Nilai voltan (V)

Positive electrodeElektrod positif

B / C 0.1 CA / C 0.8 C

Electrode Y[Elektrod Y]

Electrode X[Elektrod X]

Electrode W[Elektrod W

Electrode Z[Elektrod Z]

Potassium iodide solution[Larutan kalium iodida]

Hydrochloric acid[asid hidroklorik]

[2 marks]

3. Diagram 1 shows the set-up of apparatus to investigate the electrolysis of 0.0001 mol dm─3 of hydrochloric acid and 1.0 mol dm─3 of potassium iodide using carbon electrodes.

Rajah 1 menunjukkan susunan radas untuk mengkaji elektrolisis 0.0001 mol dm─3 hidroklorik asid dan 1.0 mol dm─3 kalium iodida dengan menggunakan elektrod karbon.

Diagram 1[Rajah 1]

(a) (i) Identify all the electrodes which serve as anode and cathode.Kenalpastikan semua elektrod yang berfungsi sebagai anod dan katod

Anode [anod]:....................................................................................................................

Cathode [katod]:................................................................................................................ [2 marks]

(ii) Name the product that is formed at electrode W.

Namakan hasil yang terbentuk pada elektrod W.

……………………………………………...……………………………………………. [1 mark]

(iii) Write the half equation for the reaction that occurs at electrode W.

Tuliskan setengah persamaan bagi tindak balas yang berlaku di elektrod W.

…………………………………………………………………………………………… [1mark]

(b) (i) State the observation at electrode Y.Nyatakan pemerhatian pada elektrod Y.

…………………………………………………………………………………………….

[1 mark]

(ii) Name the product formed in b(i)Namakan hasil yang terbentuk di b(i)

............................................................................................................................................ [ 1 mark]

(iii) Suggest a test to confirm the product in b(ii).

Cadangkan satu ujian untuk mengesahkan hasil yang terbentuk di b(ii).

………………………...………………………………………………………………….

………………….………………………………………………………………………... [2 marks]

(c) In a separate experiment, the 0.0001 mol dm─3 of hydrochloric acid is replaced with 1.0

moldm─3 of hydrochloric acid and electrolysis is carried out.Dalam experimen yang berlainan, asid hidroklorik yang berkepekatan 0.0001 mol dm─3

digantikan dengan asid hidroklorik yang berkepekatan 1.0 mol dm─3 dan elektrolisis dijalankan..

(i) State the product that will form at electrode W. Nyatakan hasil yang akan terbentuk pada elektrod W.

………………………...…………………………………………………………………. [1 mark]

(ii) Explain your answer in c(i).

Terangkan jawapan anda dalam c(i).

............................................................................................................................................

.……….………………………………………………………...………………………… [1 mark]

4 Diagram 2 shows the apparatus set-up to study the electrolysis of copper(II) nitrate solution using copper electrodes.Rajah 2 menunjukkan susunan radas untuk mengkaji elektrolisis larutan kuprum(II) nitrat dengan menggunakan elektrod kuprum.

Diagram 2

Rajah 2

Based on Diagram 2:Berdasarkan Rajah 2:

(a) Write the formulae for all the cations present in copper(II) nitrate solution.

Tulis formula bagi semua kation yang hadir dalam larutan kuprum(II) nitrat.

…………………………………………………………………………………………[1 mark]

[1 markah]

(b) (i) State the electrode that acts as a cathode. Nyatakan elektrod yang bertindak sebagai katod.

………………………………………………………………………………… [1 mark]

(ii) Name the product formed at the cathode.

Namakan hasil yang terbentuk di katod.

………………………………………………………………………………… [1 mark]

(c) The experiment has been carried out for 30 minutes and it is found that there is no

change in the intensity of the blue copper(II) nitrate solution. Explain why.

Copper electrode YElektrod kuprum Y

Copper(II) nitrate solutionLarutan kuprum(II) nitrat

Copper electrode XElektrodkuprum X

Eksperimen telah dijalankan selama 30 minit dan didapati tiada perubahan pada keamatan warna biru larutan kuprum(II) nitrat. Terangkan mengapa.

……………………………………………………………………………………..

……………………………………………………………………………………..

…………………………………………………………………………………….. [2 marks]

(d) (i) Write the half equation for the reaction that occurs at copper electrode X.Tulis setengah persamaan bagi tindak balas yang berlaku di elektrod kuprum X.

…………………………………………………………………………………[1 mark]

[1 markah]

(ii) If the electrolysis process is repeated by replacing copper electrodes with carbon electrodes, what will be observed at the electrode X?Jika proses elektrolisis diulang dengan menggantikan kedua-dua elektrod kuprum dengan elektrod karbon, apakah yang akan diperhatikan di elektrod X?

…………………………………………………………………………….......[1 mark]

[1 markah]

(e) A student intends to electroplate an iron spoon with silver metal based on the industrial application of electrolysis. Seorang pelajar ingin menyadur sebatang sudu besi dengan logam perak berdasarkan kegunaan elektrolisis dalam industri.

(i) Draw the apparatus set-up used to electroplate the iron spoon with silver metal.

Lukis susunan radas yang digunakan untuk menyadurkan sudu besi dengan logam perak.

Copper electrodesElektrod kuprum

Copper(II) sulphate solutionLarutan kuprum(II) sulfat

A

Table 9Jadual 9

Copper(II) sulphate solutionLarutan kuprum(II) sulfat

A

Carbon electrodes Elektrod karbon

[2 marks] (ii) Suggest one step that can be taken to ensure that the iron spoon is

electroplated evenly.Cadangkan satu langkah yang boleh diambil untuk memastikan penyaduran sekata pada sudu besi.

…………………………………………………………………………………[1 mark]

SECTION B AND C

1. (a) You have an impure silver plate. The impure silver plate can be purified by using an electrolysis process.

Draw a labelled diagram of the set up of the apparatus for the experiment. Anda mempunyai satu kepingan argentum tak tulen. Kepingan argentum tak tulen tersebut boleh ditulenkan melalui proses elektrolisis.

Lukiskan gambarajah berlabel susunan radas bagi eksperimen tersebut. [4 marks]

(b) Table 9 shows the set up of apparatus of two experiments to investigate electrolysis process by using different electrodes.

Jadual 9 menunjukkan susunan radas bagi dua eksperimen untuk mengkaji proses elektrolisis dengan menggunakan elektrod yang berlainan.

Experiment Eksperimen

Apparatus set-upSusunan radas

I

II

(i) Compare the observation and product formed at the anode for both experiments.Bandingkan pemerhatian dan hasil yang terbentuk di anod bagi kedua-dua

eksperimen.

(ii) Write the half equation at the anode for both experiments.Tuliskan persamaan setengah di anod bagi kedua-dua eksperimen.

[6 marks]

(c) Study the following statement. Kaji pernyataan berikut:

Describe a laboratory experiment to prove this statement by using dilute sulphuric acid as the electrolyte and two different metals. Huraikan satu eksperimen untuk membuktikan pernyataan di atas dengan menggunakan asid sulfurik cair sebagai elektrolit dan dua logam yang berlainan.

Your explanation must include:Penerangan anda mestilah mengandungi:

a labelled diagram gambar rajah berlabel

procedure prosedur

observation pemerhatian

half equationsetengah persamaan

[10 marks]

Chemical energy can be changed to electrical energy.Tenaga kimia boleh ditukarkan kepada tenaga elektrik.

0.0001 mol dm-3 potassium iodide solutionLarutan kalium iodida 0.0001 mol dm-3

A

Carbon electrode PElektrod karbon P

Carbon electrode QElektrod karbon Q

2 (a) Diagram 8.1 shows the set-up of the apparatus to study the electrolysis of potassium iodide solution.

Rajah 8.1 menunjukkan susunan radas untuk mengkaji elektrolisis larutan kalium iodida.

(i) State the ions attracted at electrode P and electrode Q.Nyatakan ion-ion yang tertarik pada elektrod P dan elektrod Q.

[2 marks]

(ii) Name the products formed at electrode P and electrode Q.Namakan hasil yang terbentuk pada elektrod P dan elektrod Q.

[2 marks]

(iii) If the experiment is repeated by using 1.0 mol dm-3 of potassium iodide solution: Name the products formed at electrode P and electrode Q Write half equations for both electrodes Describe a confirmatory test to verify the presence of the product

formed at electrode P

Sekiranya eksperimen ini diulangi dengan menggunakan larutan kalium iodida 1.0 mol dm-3: Namakan hasil yang terbentuk pada elektrod P dan elektrod Q Tulis setengah persamaan bagi kedua-dua elektrod Huraikan ujian pengesahan untuk mengesahkan kehadiran hasil yang

terbentuk pada elektrod P

Diagram 8.1Rajah 8.1

Diagram 8.2Rajah 8.2

Copper(II) sulphatesolution

Larutan kuprum (II) sulfat

Copper kuprum Aluminium

Aluminium

V

Copper kuprum

[6 marks]

(b) Diagram 8.2 shows two type of cells.Rajah 8.2 menunjukkan dua jenis sel.

Cell X Cell Y

Compare and contrast cell X and cell Y in term of:

Type of cell The energy change The terminals of the cells Ions presence in the electrolyte Observation Half equation for both electrodes Name of the processes occurred at the positive terminal of each cell

Banding dan beza sel X dan sel Y dari segi: Jenis sel Perubahan tenaga Terminal bagi kedua-dua sel Ion-ion yang hadir dalm elektrolit Pemerhatian Setengah persamaan bagi kedua-dua elektrod Nama proses yang berlaku pada terminal positif kedua-dua sel

[10 marks]