Two faraday of electric charge produces 30g of any element X(A=45) at the cathode.What is the formula of the ion of X? the answer is X with +3 charge, any explanation pls?

1 Answer
Mar 25, 2018

The mass of the positive ion of element #X# deposited at cathode on passing #2F# of electricity is #30#g.

So the number of moles of ions deposited is #30/45=2/3#mol, where atomic mass of X is #45g"/" mol#
So the amount of charge associated with #2/3#mol ion is #2F#

Hence the amount of charge associated with 1mol ion is #2xx3/2F=3F#

By Faraday's law the amount of charge associated with 1 mole positive ion of valency #+n# is #nF#

Hence #nF=3=>n=3#

So the formula of the ion is #X^(+3)#