Question

What is the equivalent weight of $N{a}_2{S}_2{O}_3.5H_{2}O$?

• A. $240g$
• B. $246g$
• C. $248g$
• D. $250g$

Answer 1

The correct option is C $248g$

The equivalent weight is the gram molecular weight divided by the number of electrons lost or gained by each molecule.

$2N{a}_2{S}_2{O}_3+I_2⟶N{a}_2{S}_4{O}_6+2NaI$

$2N{a}_2{S}_2{O}_3\equiv I_2\equiv 2I$

Thus, $I\equiv N{a}_2{S}_2{O}_3$

Thus Molecular weight divded by 1 is the equivalent weight & hence both have same value.

Hence,Equivalent weight of $N{a}_2{S}_2{O}_3.5H_{2}O\equiv \text{molar mass}=248g$