Question

Calculate the electric current required to deposit 0.972 g of chromium in three hours. ECE of chromium is 0.00018\[g{{C}^{-1}}\]
A. 0.50 A
B. 1 A
C. Zero
D. 2.5 A

Answer 1

Hint: It was the faraday law of electrolysis that gives the relationship between all the quantities discussed above such as M (mass in gram) which is directly professional to Q (quantity of charge passed through the electrostatic solution) where Q is equal to It (as \[I\text{ }=\text{ }Q/t\]) and on removing proportionality sign we add Z (electrochemical equivalent or ECE, a constant). The Z is equal to the ratio of equivalent weight (E) to the faraday constant (F) where the faraday constant is defined as the charge on one mole of electrons (96500 C). In this question, we are directly given the electrochemical equivalent, ECE.

Complete Step by Step Answer:
In the given question we are provided with the deposited amount of chromium in three hours (convert in second), which is equal to 0.972 g, ECE is given as 0.00018 g/C. And we need to find the electric current which is passed through an electrolyte solution containing two electrodes.
When we pass current (need to calculate) in an electrolytic solution containing two electrodes, the 0.972 g amount of chromium (cation) deposited on the electrolyte (cathode which is attached with negative terminal of battery) takes 3 hours (3×60×60 seconds) and Z {E (equivalent weight)/F (faraday constant)} is given as 0.00018 g/C. So by putting all the values in the formula given above we get the current that is provided to cause electrolysis such as
\[M\text{ }\propto \text{ }Q\]
\[M\text{ }=\text{ }ZIt\]
\[0.972\text{ }=\text{ }0.00018\text{ }\times \text{ }I\times \text{ }10800\]
\[0.972\text{ }=\text{ }I\text{ }\times \text{ }1.944\]
\[I\text{ }=\text{ }0.972/1.944\]
\[I\text{ }=\text{ }0.5A\]
Thus, the correct option is A.

Note: In this process, an electrolytic solution (electrolytic cell which converts electrical energy into chemical energy) contains two electrodes (anode and cathode). Opposite to galvanic cell, in electrolytic cell anode is attached to the positive terminal of the battery (reduction takes place at this electrode or can say anode act as an oxidizing agent) and cathode is attached to the negative terminal of the battery (oxidation takes place at this electrode or can say cathode act as reducing agent). As soon as the current passed in the electrolytic solution (conducting solution) anion started to move towards the anode and action moved towards the cathode electrode in the given question chromium is deposited on the electron being cation chromium must be deposited on the cathode electrode. As per far away deposition the amount of action or anion (or can say discharge of these ions) is proportional to the charge passed to the solution.