Question

0.3605 g of a metal is deposited on the electrode bypassing 1.2 amperes of current for 15 minutes through its salt solution. The atomic weight of the metal is 96. What is the valency of the metal?

Answer 1

Weight ‘w’ of the metal = 0.3605 g
Current = 1.2 amp.
Time = 15 min = 15 × 60 sec.
The atomic weight of metal = 96
According to Faraday’s first law of electrolysis,

Electrochemical equivalent, `"Z" = "w"/("I × t")`

= `0.3605/(1.2 xx 15 xx 60) = 3.34 xx  10^-4` g c^-1

Valency = `"Atomic wt."/"Equivalent wt."`

= `96/(3.34 xx 10^-4 xx 96500) = 2.98` (∵ Equivalent wt. = Z × F)

= 3

Valency of metal is 3.