Question:
On complete reaction of $\mathrm{FeCl}_{3}$ with oxalic acid in aqueous solution containing $\mathrm{KOH}$, resulted in the formation of product A. The secondary valency of Fe in the product $A$ is ____________ .
Solution:
(6)
$\mathrm{Fe}^{3+}+3 \mathrm{~K}^{+}+3 \mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow \mathrm{K}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]$
(A) Secondary valency of Fe in 'A' is 6 .