Q. The negative $Zn$ pole of Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13 g in 30 min. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is
A) 0.180 g
B) 0.141 g
C) 0.126 g
D) 0.242 g
Explanation
(c) According to Faraday’s law of electrolysis
$\ m = zq$
$\ \frac{m_{zn}}{m_{Cu}} = \frac{z_{Zn}}{z_{Cu}}$
$\therefore\frac{0.13}{m_{Cu}} = \frac{32.5}{31.5}$
${\ m}_{Cu} =$0.126 g.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.