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Electrochemistry — Chemistry STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceChemistryElectrochemistry3 Marks
Question
A solution Ni(NO3)2 is electrolysed between platinum electrodes a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?
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Answer

Amolunt of electricity flow 
$Q = It$
I = 5 Ampere, 1 = time (in second) = 20 × 60s 
$Q =5 \times 20 \times 60=6000 C$
The reaction taking place at cathode :
$Ni ^{2+}+2 e ^{-} \rightarrow Ni$
Atomic mass of Ni = 58.7 (1 mole)
According to the reaction, 2F or 2 × 96500 C of electric current is passed to get 58.7 g Ni.
Hence, the amount of Ni obtained by passing 6000 C eletric current :
$=\frac{58.7 \times 6000}{2 \times 96500}=1.824 g$
Therefore, the amount of Ni deposited at cathode = 1.824 g.

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