Electrochemistry Test

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CHEMISTRY FORM 4 ELECTROCHEMISTRY TEST

Name :........................................................................................... Form : Answer sheet Section A 1 A B C D 6 A B C D 11 A B C D 16 A B C D

2 A B C D 7 A B C D 12 A B C D 17 A B C D




Section A Answer all question in space provided above. 1. Which of the following substances is an

electrolytes?

I Hydrochloric acid

II Solid Zinc Bromide III Molten Lead iodide

IV Solid Sodium chloride

A. I and III B. I, II and III C. I, III and IV D. I, II, III and IV

2. Why does sodium chloride conduct electricity in

molten state?

A. It is has a low melting point B. It contains ion Na+ and Cl- C. It soluble in water D. It contains free mobile ion

3. Copper (II) sulphate is and electrolyte. Which of

the following is true about copper (II) sulphate

A. It conduct electricity in solid state B. It conduct electricity in molten state only C. It conduct electricity in molten and solid

state. D. It conduct electricity in molten and aqueous

state.

4. The figure shows the set up of the apparatus for the electrolysis of molten lead (II) bromide.

Which of the following observations at

anode and cathode is correct

Anode Cathode

A. Colourless gas is liberated

Brown bead is deposited

B. Brown gas is liberated

Shiny grey bead is formed

C. Shiny grey besd is formed

Brown gas is liberated

D. Colourless gas is liberated

Shiny grey bead is formed

5. What are the ions present in an aqueous

solution of copper (II) sulphate?

A. Cu2+ , SO4- and OH-

B. Cu2+, H+, SO42- and OH-

C. Cu2+, H+, SO42- and O2-

D. Cu2+, H+, SO4

- and O2-


6. Which reaction takes place at the anode during the electrolysis of copper (II) sulphate solution using copper electrodes?

A. Cu2+ + 2e Cu B. 4OH- 2H2O + O2 + 4e C. Cu Cu2+ + 2e D. 2H+ + 2e H2

7. When aqueous solution of copper (II) sulphate is

electrolysed using copper electrodes, which of the following are observed?

I Hydrogen gas is liberated at cathode II Anode become thinner

III Brown solid deposit at cathode IV Oxygen gas is liberated at anode

A. I and II B. II and III

C. I, II and III D. II, III and IV

8. The figures shows the electrolysis of

concentrated potassium chloride solution.

What are the product formed at electrode X

and Y?

Electrode X Electrode Y A. Potassium Chlorine gas B. Hydrogen gas Chlorine gas C. Hydrogen gas Oxygen gas D. Potassium Oxygen gas

9. Which of the following electrolytes when electrolyses will yield the same product as sodium nitrate solution using graphite electrodes?

A. Aqueous silver nitrate solution B. Aqueous copper (II) sulphate solution

C. Aqueous potassium sulphate solution D. Molten copper (II) nitrate solution

10. Cryolite is added to aluminium oxide in the

extraction of aluminium from its ore. What is the function of cryolite?

A. To increase the temperature of the mixture B. To increase the rate of the electrolysis

C. To reduce the melting point of aluminium oxide

D. To reduce the heat during electrolysis. 11. The gas collected at the carbon anode in an

electrolytic cell relights a glowing wooden splinter.

Which of the following is the electrolyte contained in the cell?

A. Molten zinc chloride B. Copper (II) sulphate solution

C. A concentrated hydrochloric acid D. Molten naphthalene

12. The figure shows the electrolysis of a

concentration of sodium chloride solution using graphite electrodes.

What are the colours of litmus paper after

the electrolysis started

Litmus Paper X Litmus Paper Y A. Blue Red B. White (bleach) White (bleach) C. Red Blue D. Blue White (bleach)

Electrode Y Electrode X

_ +


13. Two metals, X and Y, are immersed in sodium chloride solution as shown in diagram below

Metal X is a negative terminal. What metals

could X and Y

X Y A. Lead Zinc B. Magnesium Lead C. Silver Lead D. Copper Ion

14. A solid deposit of element R is formed at the

cathode when aqueous solution containing ions of R is electrolysed. Which statement about element R is correct?

A. R forms negative ions B. R ions gain electrons at cathode

C. R ions lose electrons at the cathode D. R is above hydrogen in electrochemical

series. 15. Which of the following processes are carried out

using electrolysis?

I Extraction of aluminium from its ore II Coating iron with copper to make it

more durable

III Mixing tin and zinc to form alloy IV Removal the impurities from copper

metal

A. I and II B. I, II and III

C. I, II and IV D. II, III and IV

16. Diagram below shows the set-up of the apparatus used by a student to electroplate an iron rod with silver metal

The experiment was unsuccesful. The set-up

should be corrected by

A. Using alternating current B. Reversing the terminals of batery C. Cleaning the zinc rod with sand paper D. Remove the ammeter.

17. Diagram below shows a Daniel cell

Which of the following actions will decrease the

voltage of the cell?

A. Replace the zinc plate with aluminium plate B. Replace the zinc plate with magnesium

plate C. Replace the copper plate with silver plate D. Replace the copper plate with iron plate.

18. A student carry out electrolysis process on

concentrated potassium chloride solution. What is the product obtained at cathode?

A. Potassium deposit B. Hydrogen gas

C. Oxygen gas D. Chlorine gas

Silver plate

Silver nitrate solution

Iron rod

Copper plate

CuSO4 aq

Zinc plate

ZnNO3 aq

Salt Bridge


A

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

Carbon electrode Y Elektrod karbon Y

Carbon electrode X Elektrod karbon X

19. Table below gives information about three

simple cells.

Metal at negative terminal

Metal at positive terminal

Diferrent potential

(V) K Fe 0.20 L Fe 1.40 Fe M 0.68

What is the potential difference of the pair of

matals K and M?

A. 0.48 B. 0.72 C. 0.88 D. 1.20

20. Diagram below shows the formation of a grey

metal when metal Q is immersed into zinc nitrate solution

What is metal Q?

A. Iron B. Magnesium C. Copper D. Zinc

Section B Answer all question

1. Diagram 1.1 shows the set-up apparatus to investigate the electrolysis of dilute copper (II)

sulphate solution. Rajah 1.1 menunjukkan susunan radas untuk mengkaji elektrolisis larutan kuprum (II) sulfat cair.

Diagram 1.1 /Rajah 1.1

a. i. What is meant by cation? Apakah yang dimaksudkan dengan kation? ............................................................................................................................................... [1 mark] ii. What is the energy change that occurs in the electrolysis process? Apakah perubahan tenaga yang berlaku dalam proses elektrolisis itu? ............................................................................................................................................... [1 mark]

Zinc nitrate Zinc metal

Metal Q


b. In the electrolysis of dilute copper (II) sulphate solution: Di dalam proses elektrolisis larutan kuprum (II) sulfat cair: i. In the table below write the ions in b(i) which moved to electrodes X and Y Di dalam jadual dibawah tuliskan ion-ion di dalam b(i) yang bergerak ke elektrod X dan Y [2 marks]

Elektrode X / Elektrod X Electrode Y / Elektrod Y

ii. What would you observe at electrode X? Apakah yang akan anda perhatikan pada elektrod X? ............................................................................................................................................... [1 mark] Name the product at electrod X and Y Namakan hasil yang terhasil pada elektrod X dan elektrod Y [2 marks]

Elektrode X / Elektrod X Electrode Y / Elektrod Y

iii. What would you observe at electrode Y? Apakah yang akan anda perhatikan pada elektrod Y? ............................................................................................................................................... [1 mark] iv. Write the ionic equation at electrode X and Y Tuliskan persamaan ion pada elektrod X dan elektrod Y Electrode X / Elektrod X :...................................................................................................... Electrode Y / Elektrod Y :....................................................................................................... [2 marks] v. State the confirmation test for the product at electrode X Nyatakan ujian pengesahan ke atas hasil yang terhasil pada elektrod X ............................................................................................................................................... [1 mark]


2. Diagram 2.1 shows the set up of apparatus of a chemical cell. Rajah 2.1 menunjukkan susunan radas sel kimia.

Diagram 2.1

(a) Mark the direction of the flow of electrons in the above diagram. Tandakan arah pengaliran elektron pada rajah di atas. [1 mark] (b) (i) What is the function of the salt bridge? Apakah fungsi titian garam? …………………………………………………………………………………………………………………………………………………… [1 mark] (ii) Suggest a suitable chemical substance to be used as salt bridge Cadangkan bahan kimia yang sesuai untuk digunakan sebagai titian garam …………………………………………………………………………………………………………………………………………………... [1 mark] (c) State the energy change in the cell above. Nyatakan perubahan tenaga yang berlaku dalam sel di atas. …………………………………………………………………………………………………………………………………………………………… [1 mark] (d) (i) State the negative terminal Nyatakan terminal negatif. …………………………………………………………………………………………………………………………………………………… [1 mark] (ii) Explain your answer in d(i). Terangkan jawapan anda di (d)(i). ……………………………………………………………………………………………………………………………………………………

Magnesium

Magnesium nitrate solution

Copper

Copper (II) nitrates solution


[1 mark] (e) (i) State one observation at the copper electrode. Nyatakan satu pemerhatian pada elektrod kuprum …………………………………………………………………………………………………………………………………………………… [1 mark] (ii) Write the half equation for the reaction in (e) (i). Tuliskan persamaan setengah bagi tindakbalas di (e) (i). …………………………………………………………………………………………………………………………………………………… [1 mark] (f) (i) State one observation at the magnesium electrode. Nyatakan satu pemerhatian pada elektrod magnesium …………………………………………………………………………………………………………………………………………………… [1 mark] (ii) Write the half equation for the reaction in (f) (i). Tuliskan persamaan setengah bagi tindakbalas di (f) (i). …………………………………………………………………………………………………………………………………………………… [1 mark]

End of question

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Electrochemistry Test