Question

At $298\, K$, the standard reduction potentials are $1.51\, V$ for $MnO _{4}^{-} \mid Mn ^{2+} 1.36\, V$ for $Cl _{2} \mid Cl ^{-} 1.07\, V$ for $Br _{2} \mid Br ^{-}$, and $0.54\, V$ for $\left. H _{2}\right|^{-}$. At $pH =3$, permanganate is expected to oxidize: $\left(\frac{R T}{F}=0.059\, V \right)$

• A. $Cl ^{-}, Br ^{-}$ and $I ^{-}$
• B. $Cl ^{-}$ and $Br ^{-}$
• C. $Br ^{-}$ and $I ^{-}$
• D. $I^-$ only

Answer 1

Answer: (C)

Permanganate is expected to oxidise $Cl ^{-}, Br ^{-}$ and $I ^{-}$ due to $E_{\text {eell }}^{\circ}>0$.