Balance the following redox reactions:
${C r}_{2} O_{7}^{2 -} (a q) + H {N O}_{2} (a q) ⟶ {C r}^{3 +} (a q) + {N O}_{3}^{-} (a q)$

{C r}_{2} O_{7}^{2 -} (a q) + {3 N O}_{2}^{-} (a q) + {8 H}^{+} (a q) ⟶ {2 C r}^{3 +} (a q) + {6 N O}_{3}^{-} (a q) + {4 H}_{2} O (l)

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{C r}_{2} O_{7}^{2 -} (a q) + {6 N O}_{2}^{-} (a q) + {8 H}^{+} (a q) ⟶ {2 C r}^{3 +} (a q) + {6 N O}_{3}^{-} (a q) + {4 H}_{2} O (l)

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{C r}_{2} O_{7}^{2 -} (a q) + {3 N O}_{2}^{-} (a q) + {8 H}^{+} (a q) ⟶ {2 C r}^{3 +} (a q) + {3 N O}_{3}^{-} (a q) + {4 H}_{2} O (l)

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{C r}_{2} O_{7}^{2 -} (a q) + {6 N O}_{2}^{-} (a q) + {8 H}^{+} (a q) ⟶ {2 C r}^{3 +} (a q) + {3 N O}_{3}^{-} (a q) + {4 H}_{2} O (l)

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Solution

The correct option is B ${C r}_{2} O_{7}^{2 -} (a q) + {3 N O}_{2}^{-} (a q) + {8 H}^{+} (a q) ⟶ {2 C r}^{3 +} (a q) + {3 N O}_{3}^{-} (a q) + {4 H}_{2} O (l)$
The unbalanced chemical equation is as follows:
${C r}_{2} O_{7}^{2 -} (a q) + H {N O}_{2} (a q) ⟶ {C r}^{3 +} (a q) + {N O}_{3}^{-} (a q)$
Balance all atoms other than H and O.
${C r}_{2} O_{7}^{2 -} (a q) + H {N O}_{2} (a q) ⟶ 2 {C r}^{3 +} (a q) + {N O}_{3}^{-} (a q)$
The oxidation number of Cr changes from +6 to +3. The change in the oxidation number is 3.
Total change in the oxidation number is 6.
The oxidation number of N changes from +3 to +5. The change in the oxidation number is 2.
To balance the increase in the oxidation number with decrease in oxidation number, multiply $N O_{2}^{-}$ and $N O_{3}^{-}$ with 3.
${C r}_{2} O_{7}^{2 -} (a q) + H^{+} + 3 {N O}_{2}^{-} (a q) ⟶ 2 {C r}^{3 +} (a q) + 3 {N O}_{3}^{-} (a q)$
Balance the O atoms by adding 4 water molecules on RHS.
${C r}_{2} O_{7}^{2 -} (a q) + H^{+} + 3 {N O}_{2}^{-} (a q) ⟶ 2 {C r}^{3 +} (a q) + 3 {N O}_{3}^{-} (a q) + 4 H_{2} O$
Balance H atoms by adding 7 $H^{+}$ ions on LHS.
${C r}_{2} O_{7}^{2 -} (a q) + 8 H^{+} + 3 {N O}_{2}^{-} (a q) ⟶ 2 {C r}^{3 +} (a q) + 3 {N O}_{3}^{-} (a q) + 4 H_{2} O$
This is the balanced chemical equation.

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Similar questions

Q. Choose correct statement(s) regarding the following reaction.

{C r}_{2} O_{7}^{2 -} (a q) + 3 {S O}_{3}^{2 -} (a q) + 8 H^{+} ⟶ 2 {C r}^{3 +} (a q) + 3 {S O}_{4}^{2 -} (a q) + 4 H_{2} O

Q. The cell reaction

{C r}_{2} O_{7}^{2 +} (a q) + 14 H^{+} (a q) + 6 {F e}^{2 +} (a q) \to 6 {F e}^{3 +} (a q) + 2 {C r}^{3 +} (a q) + 7 H_{2} O (l)

, is best represented by:

Q. Balance the redox reaction by Half reaction method.

{F e}^{2 +} (a q) + {C r}_{2} O_{7}^{2 -} (a q) (acid medium) - ------- \to {F e}^{3 +} (a q) + {C r}^{3 +} (a q)

Balanced ionic equation for the reaction of Potassium Dichromate (VI) K₂Cr₂O₇ with Sodium Sulphite Na₂SO₃ in acid solution to give Chromium (III) ion and sulphate ion is

Write balanced redox reactions of the following:

H_{2} O_{2} (a q)

reduces

{C r}_{2} O_{7}^{2 -} (a q)

to green coloured

{C r}^{3 +} (a q)

in acidic medium.

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Balance the following redox reactions:Cr2O2−7(aq)+HNO2(aq)⟶Cr3+(aq)+NO−3(aq)

Balance the following redox reactions:
${C r}_{2} O_{7}^{2 -} (a q) + H {N O}_{2} (a q) ⟶ {C r}^{3 +} (a q) + {N O}_{3}^{-} (a q)$