Redox Reactions MCQs for NEET — Chemistry Questions with Answers

2.

2KMnO₄ + 10FeSO₄(NH₄)₂SO₄.6H₂O+8H₂O → K₂SO₄+ 2MnSO₄+ 5Fe₂(SO₄)₃+ 10(NH₄)₂SO₄+ 68H₂O

The ionic equation involved in the process is given below.

Oxidation half reaction – [Fe²⁺ → Fe³⁺ – e^–] x 5

Reduction half reaction – MnO₄^– + 8H⁺ + 5e^– → Mn²⁺ + 4H₂O

Overall ionic equation – MnO₄^– + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O

(a)

 $$\begin{gathered} 2{\mathrm{I}}^{-} \stackrel{ }{\to } {\mathrm{I}}_2^0 + 2e \\ 2e + {\mathrm{O}}_2^{1-} \stackrel{ }{\to }2{\mathrm{O}}^{2-} \end{gathered}$$

(d) $$\begin{gathered} 5e + {\mathrm{Mn}}^{7+}\stackrel{ }{\to } {\mathrm{Mn}}^{2+} \\ {\mathrm{O}}_2^{1-}\stackrel{ }{\to }{\mathrm{O}}_2^0 +2e \end{gathered}$$

(b) $$\begin{gathered} {\mathrm{O}}_2^{1-} + 2e \stackrel{ }{\to }2{\mathrm{O}}^{2-} (\mathrm{As} \mathrm{oxident}) \\ {\mathrm{O}}_2^{1-} \stackrel{ }{\to } {\mathrm{O}}_2^{\stackrel{.}{0}} + 2e (\mathrm{As} \mathrm{reductant}) \end{gathered}$$

 $$\begin{gathered} \mathrm{PbS} + 4{\mathrm{H}}_2{\mathrm{O}}_2 \stackrel{ }{\to }{\mathrm{PbSO}}_4 +4{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Black} \mathrm{White} \end{gathered}$$

K2​Cr2​O7​+H2​SO4​→K2​SO4​+H2​Cr2​O7​
H2​Cr2​O7​+4H2​O2​→2CrO5​+5H2​O

An acid solution of potassium ferrocyanide is oxidised by hydrogen peroxide to potassium ferricyanide

2K4FeC6N6 + H2O2 = 2K3FeC6N6 + 2KOH

Hydrogen peroxide on treatment with a acidified solution of Titanium salt gives a Yellow or Orange colour due to the formation of pertitanic acid.