Question

Potassium dichromate is used

• A. in electroplating
• B. as a reducing agent
• C. it oxidizes ferrous ions into ferric ions in acidic media as an oxidizing agent
• D. as an insecticide

Answer 1

Answer: (C)

Potassium dichromate is an oxidizing agent it oxidizes ferrous ions into ferric ions in acid medium.
$ Cr _{2} O _{7}^{2-}+14 H ^{+}+6 e^{-} \longrightarrow 2 Cr ^{3+}+7 H _{2} O $
$\left[ Fe ^{2+}\right. \left.\longrightarrow Fe ^{3+}+e^{-}\right] \times 6 $
$ Cr _{2} O _{7}^{2-}+6 Fe ^{2+}+14 H ^{+} \longrightarrow $
$ 6 Fe ^{3+}+2 Cr ^{3+}+7 H _{2} O $