an aqueous solution of unknown salt of Pd is electrolysed by a current of 3.0 A passing for 1 hr. during electrolysis 2.977 g of Pd ions are reduced at cathode. what is the charge on palladium ions in solution?
Answers
The charge on Palladium ions in the solution is 4+, i.e, palladium ions exist as Pd4+ in the given solution.
• Let us consider that the charge on Palladium ions is x+ .
• Reaction at cathode :
Pdx+ + xe- --> Pd
Since the palladium ions are deposited at cathode, the ions bear a positive charge, because we know that cations are deposited at cathode.
• Given,
Current passing through the solution (I) = 3 A
Time (t) = 1 hour = 60 × 60 sec
Weight of Pd ions reduced at cathode = 2.977 g
Now we have to apply Faraday's first law of electrolysis, which is stated as follows to calculate the charge on Pd ions.
w / eq wt. = (I × t) / 96500
Where, w denotes the weight of Pdx+ ions deposited,
eq wt. is the equivalent weight of Pd,
I is the current flowing,
and t is the time for which the current flows
• eq wt. of Pd = molecular weight / valency
=> eq wt. = 106.4 / x
Therefore,
2.977 / (106.4/x) = (3 × 1 × 60 × 60) / 96500
=> ( 2.977 × x ) / 106.4 = 0.1119
=> x = (0.1119 × 106.4) / 2.977
=> x = 3.999
=> x = 4
Therefore, the charge on Pd ions in the solution is +4 .