Question

The chemical equivalent of silver is 108. If the current in a silver voltammeter is 2 Amp. The time required to deposit 27 grams of silver will be
A. 8.57 hrs
B. 6.70 hrs
C. 3.35 hrs
D. 12.50 hrs

Answer 1

Hint: The Silver ion will get deposited on the cathode by liberating one electron from its valence shell. According to Faraday’s first law of electrolysis, the amount of ion deposited is proportional to the electric current and the time period.

Formula Used:\[m = Zit\], where m is the mass of ion deposited, Z is the electrochemical equivalent, i is the electric current and t is the time and Z is the electric equivalence of the electrolyte.

Complete answer:It is given that the chemical equivalence of silver is 108
\[E = 108\]
The current in the silver voltammeter is given as 2Amp.
\[i = 2A\]
The mass of the silver deposited is given as 27 grams.
Using Faraday’s first law of electrolysis,
\[m = Zit\]
The time required to deposit the silver can be determined as,
\[t = \dfrac{m}{{Zi}}\]
The electrochemical equivalent can be obtained using the chemical equivalence as,
\[Z = \dfrac{E}{F}\]
\[Z = \dfrac{{108}}{{96500}}\]
Putting the values, we get
\[t = \dfrac{{27 \times 96500}}{{108 \times 2}}s\]
\[t = 12062.5s\]
On changing the unit of the time obtained from seconds to hours, we get
\[t = \dfrac{{12062.5}}{{3600}}h\]
\[t = 3.35h\]
So, the required time to deposit the given amount of silver is 3.35 hours.
 Therefore,

the correct option is (C).

Note: In the question we have given the chemical equivalence of the silver but in Faraday’s law of electrolysis, we need to use the electro-chemical equivalent of the silver. So, we should be careful about the given quantity. We change the chemical equivalent to the electrochemical equivalent of silver.