Question

Calculate the n-factor of $S_2{O}_3$ for the following change.
$2S_2{O}_3^{2-}\to S_4{O}_6^{2-}+2e^{-}$

• A. 1
• B. 0.5
• C. 2
• D. None of these

Answer 1

The correct option is A 1

Steps for finding valency factor/n-factor:
1. Find the oxidation state (O.S.) of metal in reactant side.
2. Find the oxidation state of metal in product side.
3. Take the magnitude of difference of two oxidation state $|O.S{.}_{Product}-O.S{.}_{Reactant}|\times \text{number of atom}$ for the valency factor
$2S_2{O}_3^{2-}\to S_4{O}_6^{2-}+2e^{-}$
O.S. of S in reactant side
$\Rightarrow 2x+3\times (-2)=-2$
$\Rightarrow x=+2$

O.S. of S in product side
$\Rightarrow 4x+6\times (-2)=-2$
$\Rightarrow x=+2.5$
$\text{valency factor}=\text{number of S atom}\times |O.S{.}_{Product}-O.S{.}_{Reactant}|$
$\text{valency factor}=2\times |+2.5-2|$
$\text{valency factor}=1$
n-factor of $S_2{O}_3^{2-}=\text{number of sulphur atom}\times |O.S{.}_{Product}-O.S{.}_{Reactant}|=2\times 0.5=1$