Assuming that copper contains by iron, silver and gold as impurities. After passage of 12.4 A for 4825 sec , the mass of anode decreased by 20.00 gm and the cathode increased by 19.05 gm . The mass pe

Question

Assuming that copper contains by iron, silver and gold as impurities. After passage of 12.4 A for 4825 sec , the mass of anode decreased by 20.00 gm and the cathode increased by 19.05 gm . The mass percent of iron in the impure copper sample is ( Cu = 63.5 , Fe = 56 )

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Total equivalents of charge passed: T o t a lEq = 96500 I × t ​ = 96500 12.4 × 4825 ​ = 0.62 Equivalents of Cu deposited at cathode: E q C u ​ = Eq . wt M a ss ​ = 63.5/2 19.05 ​ = 0.60 Equivalents of Fe dissolved at anode: Since Ag and Au remain undissolved as anode mud, E q F e ​ = T o t a lEq − E q C u ​ = 0.62 − 0.60 = 0.02 Mass of iron dissolved: M a s s F e ​ = E q F e ​ × ( n − f a c t or A t o mi c ma ss ​ ) = 0.02 × 2 56 ​ = 0.56 g Mass percent of iron in the sample: % F e = 20.00 g 0.56 g ​ × 100 = 2.80%

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