Question

For depositing 1gm of Cu in copper voltameter on passing 2 amperes of current, the time required will be (For copper Z=0.00033 gm/C).
A. Approx. 20 minutes
B. Approx. 25 minutes
C. Approx 30 minutes
D. Approx 35 minutes

Answer 1

Hint: For solving the given problem, we need to apply the concept of Faraday’s first law of electrolysis. This law gives us some mathematical formula in which we need to substitute the corresponding values and find the required time.

Formula used: $m=Zit$.

Complete Step by Step Answer:
According to Faraday's first electrolysis law, the amount of reaction occurring in terms of the mass of ions created or released from an electrolyte is proportionate to the amount of electric current. Since the amount of coulombs (Q) flowing in a second equals the amount of electric current (ampere), we can write,
$m=Zq$
Amperes are used to measure the charges flowing per unit of time (seconds) termed electric current. Therefore,
$i=\dfrac{q}{t}$
On rearranging we get,
$q=it$
Substituting the value of q in the mathematical expression of Faraday’s, we get the final equation for solving the problem as,
$m=Zit$
As given in the problem,
$m=1gm$,
$Z=0.00033 gm/C$,
$i=2 A$
Substituting all the values in the formula we get,
$1=\lgroup0.33\times 10^{-3}\rgroup\lgroup2\rgroup~t$
$\Rightarrow~t=\dfrac{10^{3}}{0.66}=1515sec$
$\Rightarrow~t\approx25~minutes$
Therefore, the time required will be approx 25 minutes.
The correct option is B.

Note: It is to be noted that Z is the proportionality constant that can be termed as the characteristic or element of which the electrode is made in the process of electrolysis.