Question

Same quantity of electricity is being used to liberate iodine (at anode) and a metal x (at cathode). The mass of x liberated is $0.617$ g and the iodine liberated is completely reduced by $46.3$ cc of $0.124$ M sodium thiosulphate. Find the equivalent mass of metal x.

• A. $E_{q.wt}=56.468$
• B. $E_{q.wt}=147.468$
• C. $E_{q.wt}=107.468$
• D. None of these

Answer 1

The correct option is C $E_{q.wt}=107.468$

Equivalence mass of iodine is $126.9$ g
$2N{a}_2{S}_2{O}_3+I_2\to N{a}_2{S}_4{O}_6+2NaI$
The number of moles of iodine $=0.5\times \frac{46.3}{1000}\times 0.124=0.002871$ moles
The mass of iodine liberated is $0.002871\times 253.8=0.728$ g.
The equivalent mass of metal x $=$ the equivalent mass of iodine $\times \frac{\text{mass of metal x liberated}}{\text{mass of iodine liberated}}=126.9\times \frac{0.617}{0.728}=107.468$