The negative Zn pole of Daniel cell, sending a constant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the chemical equivalent of Zn and Cu and 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is :

0.180 g

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0.141g

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0.126 g

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0.242 g

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Solution

The correct option is A 0.126 g
According to Faraday's second law,

$\frac{D e c r e a s e i n m a s s o f z i n c}{C h e m i c a l e q u i v a l e n t o f z i n c} = \frac{I n c r e a s e i n m a s s o f c o p p e r}{C h e m i c a l e q u i v a l e n t o f c o p p e r}$ .

Substitute values in the above reaction.
$\frac{0.13}{32.5} = \frac{I n c r e a s e i n m a s s o f c o p p e r}{31.5}$
Hence,
$I n c r e a s e i n m a s s o f c o p p e r = \frac{31.5 \times 0.13}{32.5} = 0.126$

Option C is correct.

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