118.8cm² surface of the copper cathode of a voltameter is to be coated with 10^-6m thick copper of density 9 x 10³kgm^-3. How long will the process run with 10A constant current?
[3.3 x 10^-7kgC^-1]

5.4 min

10.8 min

15.0 min

20.0 min

Correct answer is A

From faradays law, M = itz
But mass, M = volume x density
and volume = cross sectional area x thickness
M = 118.8cm² x 10^-6 x 9 x 10³
∴ 118.8cm² x 10^-6 x 9 x 10³ = 10 x t x 3.3 x 10^-7
∴ (118.8 x 9) x 10^-7 = 10 x t x 3.3 x 10^-7

∴ t = \(\frac{118.8 \times 9}{ 3.3}\)

t = 324 seconds

Convert to minutes by dividing by 60

t = \(\frac{324}{60}\)

t = 5.4 sec

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118.8cm² surface of the copper cathode of a voltameter is to be coated with 10^-6m thick copper of density 9 x 10³kgm^-3. How long will the process run with 10A constant current?
[3.3 x 10^-7kgC^-1]

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118.8cm² surface of the copper cathode of a voltameter is to be coated with 10^-6m thick copper of density 9 x 10³kgm^-3. How long will the process run with 10A constant current?
[3.3 x 10^-7kgC^-1]