A solution contains 0.10 mol AgNO3 and 0.10 mol Cu(NO3)2. It is electrolysed between platinum electrodes and 0.25 F of charge is passed. Given E deg(Ag+/Ag) = 0.80 V, E deg(Cu^2+/Cu) = 0.34 V, Ag = 108, Cu = 63.5, and assuming each ion is completely discharged before the next starts, the total mass of metal deposited at the cathode is

JEE Advanced levelSingle correct optionDifficulty 3 of 3ec134

A solution contains $0.10 mol$ $AgNO X_{3}$ and $0.10 mol$ $Cu (NO X_{3}) X_{2}$ . It is electrolysed between platinum electrodes and $0.25 F$ of charge is passed. Given $E^{\circ} (Ag X^{+} / Ag) = 0.80 V$ , $E^{\circ} (Cu X^{2 +} / Cu) = 0.34 V$ , Ag = 108, Cu = 63.5, and assuming each ion is completely discharged before the next starts, the total mass of metal deposited at the cathode is

The ion with the higher reduction potential,

Ag X^{+}

, is discharged first.

0.10 mol

Ag X^{+}

needs

0.10 F

and gives

10.8 g

Ag. The remaining

0.15 F

reduces

Cu X^{2 +}

0.15/2 = 0.075 mol

= 4.76 g

(less than the

0.10 mol

available). Total

= 10.8 + 4.76 = 15.56 g

. Option (B) wrongly assumes all the copper is also deposited and (A) treats all the charge as going to copper.