Question

The heat generated in a coil of resistance $180$ $\Omega$ which is connected to a silver voltameter is $364.5$ kJ. If a steady current is passed through the circuit for $15$ min, find the mass of Ag that gets deposited on the cathode. The relative atomic mass of silver is $108$ g and Faraday's constant is 96,500 C.

• A. $15$ g
• B. $1.5$ g
• C. $150$ g
• D. $0.015$ g

Answer 1

The correct option is B $1.5$ g

$H=I^{2}RT$

$H=364.5kJ$

$R=180\Omega$

$t=15mins=900secs$

So $I=\sqrt{\frac{H}{RT}}=1.5A$

Now charge, $1.5\times 900=1350C$

Electrochemical equivalent $z=\frac{108}{96500}=0.001111$

Now again $z=\frac{weightofsubstance}{quantityofelectricity}$

or, $0.0011=\frac{w}{1350}$

$w=0.0011\times 1350=1.5g$