A brass plate having surface area 200 cm2 on one side is electroplated with 0.10 mm thick silver layers on both sides using a 15 A current. Find the time taken to do the job. The specific gravity of silver is 10.5 and its atomic weight is 107.9 g mol–1.


Given-
Current passing, i = 15 A
Surface area of the plate = 200 cm2,
Thickness of silver deposited= 0.1 mm = 0.01 cm



Volume of Ag deposited on one side = 200 × 0.01 cm3 = 2 cm3



 Volume of Ag deposited on both side = 2 ×2 cm3 = 4 cm3


The specific gravity of silver = 10.5


Atomic weight = 107.9 g mol–1



Now, mass of silver deposited, m can be calculated



m = Volume × Specific gravity × 1000


putting the value in the above formula, we get


= 4 × 10-3 × 10.5 ×1000


= 42 kg



Using the formula, from faraday’s law of electrolysis –



where,


m = the mass of the substance deposited on the electrode


z=electrochemical equivalence


i=current passing


t=time taken


Substituting the values






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