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Chemistry Form 4 • MODULE

(c) What is the function of the porous pot in cell A?
Apakah fungsi pasu berliang dalam Sel A?
To allow the movement of ions through it.
(d) Referring to Cell A.
Merujuk kepada Sel A.
(i) What is the observation at zinc electrode?
Apakah pemerhatian di elektrod zink?
Zinc electrode becomes thinner.

(ii) Write the half equation for the reaction at zinc electrode.
Tuliskan persamaan setengah untuk tindak balas di elektrod zink.
2+
Zn Zn + 2e
(iii) What is the observation at copper electrode / Apakah pemerhatian di elektrod kuprum?
Brown solid deposited.
(iv) Write the half equation for the reaction at copper electrode.
Tuliskan persamaan setengah untuk tindak balas di elektrod kuprum.
Cu + 2e Cu .
2+
(v) After 30 minutes, what is the colour change of the copper(II) sulphate solution? Explain why.
Selepas 30 minit, apakah perubahan warna larutan kuprum(II) sulfat? Jelaskan mengapa.
– The intensity of blue colour decreases.
– Copper(II) ions are discharged to form copper atoms.

– Concentration of copper(II) ions in copper(II) sulphate decreases.

(e) Referring to Cell B.
Merujuk kepada Sel B.
(i) What is the observation at the anode?
Apakah pemerhatian di anod?
Copper electrode becomes thinner.

(ii) Write the half equation for the reaction at the anode.
Tuliskan persamaan setengah untuk tindak balas di anod.
Cu Cu + 2e
2+
(iii) What is the observation at the cathode?
Apakah pemerhatian di katod?
Brown solid deposited.

(iv) Write the half equation for the reaction at copper electrode.
Tuliskan persamaan setengah untuk tindak balas di katod.
Cu + 2e Cu
2+
(f) The intensity of blue colour of copper(II) sulphate solution in the Cell B remains unchanged during the experiment.
Explain why.
Keamatan warna biru larutan kuprum(II) sulfat dalam Sel B tidak berubah semasa eksperimen. Jelaskan mengapa.
– The concentration of copper(II) sulphate remain unchanged.
– The rate of copper(II) ions discharged to copper atom at the cathode equals to the rate of copper atoms form

copper(II) ions at the anode.

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05-Chem F4 (3P).indd 111 12/9/2011 5:56:32 PM