A current of 3 amperes is passed for 5 hours through a molten metal salt which deposits 31.6 g of metal `("molecular mass"=177 g mol^(-1))`. What is the valency of the metal ?

Explanation

According to Faraday's first law of electrolysis.
`W=ZxxIxxt" or "Z=(W)/(Ixxt)`
`W=31.6 g,I=3 " amperes ",t=5xx60xx60s`
`Z=((31.6 g))/((3 A)xx(5xx60xx60s))=5.85xx10^(-4) "g "C^(-1)`
Now, equivalent mass (E ) `=FxxZ=(96500" C mol"^(-1))xx(5.85xx10^(-4) " g " C^(-1))`
Valency `=("Molecular mass")/("Equivalent mass")=((177" g mol"^(-1)))/((96500" C mol"^(-1))xx(5.85xx10^(-4)" g C^(-1)))=3.13~~3`.