JEE Main 2017 · Chemistry · Electrochemistry · easy

The same quantity of electricity is passed through two cells in series, one containing AgNO3 solution and the other CuSO4 solution, with inert…

Single correct option

The same quantity of electricity is passed through two cells in series, one containing

\mathrm{AgNO_3}

solution and the other

\mathrm{CuSO_4}

solution, with inert electrodes. A current of

0.50\ \mathrm{A}

deposits

1.08\ \mathrm{g}

of silver. The mass of copper deposited and the time of electrolysis are respectively (Ag

=108

, Cu

=63.5

F=96500\ \mathrm{C\,mol^{-1}}

)

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Answer: (C) $0.318\ \mathrm{g}$ and $1930\ \mathrm{s}$

1.08\ \mathrm{g\ Ag}=0.0100

mol, which needs

0.0100\ F=965

C. Time

=965/0.50=1930

s. The same charge deposits

0.0100/2=0.00500

mol Cu since

\mathrm{Cu^{2+}}+2e^-\to\mathrm{Cu}

: mass

=0.00500\times63.5=0.318

g. The other options either forget the factor of 2 for copper or the current.

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