Question

The electrochemical equivalent of a metal is $3.3\times {10}^{-7}kg$ per coulomb. The mass of the metal liberated at the cathode when a 3 A current is passed for 2 seconds will be

• A. $19.8\times {10}^{-7}kg$
• B. $9.9\times {10}^{-7}kg$
• C. $6.6\times {10}^{-7}kg$
• D. $1.1\times {10}^{-7}kg$

Answer 1

The correct option is A $19.8\times {10}^{-7}kg$

Using Faraday's first law, mass liberated at cathode is $m=zIt$ where $z=$ electrochemical equivalent, $I=$ current and $t=$ time.
here, $m=3.3\times {10}^{-7}\times 3\times 2=19.8\times {10}^{-7}kg$