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NCERT Class XII Chemistry
Chapter - Electrochemistry
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Question : 15 of 32
Marks: +1, -0
A solution of Ni(NO3)2\mathrm{Ni}(\mathrm{NO}_3)_2 is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode? (At. mass of Ni = 58.7)
Solution:  
Ni(NO3)2→Ni2++2NO3−\mathrm{Ni}(\mathrm{NO}_3)_2 \rightarrow \mathrm{Ni}^{2+} + 2\mathrm{NO}_3^{-}
At cathode : Ni2++2e−→Ni\mathrm{Ni}^{2+} + 2e^{-} \rightarrow \mathrm{Ni}
For getting 1 mole of Ni, we require 2 Faradays of electricity.
I=5 A,t=20 min=20×60=1200 secI=5\,\mathrm{A}, t=20\,\mathrm{min}=20\times60=1200\,\mathrm{sec}
(Q=I×t=5×20×60=6000 C)(Q=I\times t=5\times20\times60=6000\,\mathrm{C})
∵2×96500 C\because 2\times96500\,\mathrm{C} of electricity will produce 58.7 g\mathrm{g} of nickel
∴  6000 C\therefore\; 6000\,\mathrm{C} of electricity will produce =58.7×60002×96500=1.825 g=\frac{58.7\times6000}{2\times96500}=1.825\,\mathrm{g} of nickel
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