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Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide.

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प्रश्न

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

दीर्घउत्तर
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उत्तर

The given redox reaction can be represented as:

\[\ce{Cl_{2(s)} + SO_{2(aq)} + H_2O_{(l)} -> Cl-_{(aq)} + SO^{2-}_{4(aq)}}\]

The oxidation half reaction is:

\[\ce{^{+4}SO_{2(aq)} -> ^{+6}SO^{2-}_{4(aq)}}\]

The oxidation number is balanced by adding two electrons as:

\[\ce{SO_{2(aq)} -> SO^{2-}_{4(aq)} + 2e-}\]

The charge is balanced by adding 4H+ ions as:

\[\ce{SO_{2(aq)} -> SO^{2-}_{4(aq)} + 4H+_{(aq)} + 2e-}\]

The O atoms and H+ ions are balanced by adding 2H2O molecules as:

\[\ce{SO_{2(aq)} + 2H_2O_{(l)} -> SO^{2-}_{4(aq)} + 4H+_{(aq)} + 2e-}\]   ....(i)

The reduction half reaction is:

\[\ce{Cl_{2(s)} -> Cl-_{(aq)}}\]

The chlorine atoms are balanced as:

\[\ce{^0Cl_{2(s)} -> ^{-1}Cl-_{(aq)}}\]

The oxidation number is balanced by adding electrons

\[\ce{Cl_{2(s)} + 2e- -> 2Cl-_{(aq)}}\]  ....(ii)

The balanced chemical equation can be obtained by adding equation (i) and (ii) as:

\[\ce{Cl_{2(s)} + SO_{2(aq)} + 2H_2O_{(l)} ->  2Cl-_{(aq)} + SO^{2-}_{4(aq)} + 4H+_{(aq)}}\]

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पाठ 7: Redox Reactions - EXERCISES [पृष्ठ २८२]

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एनसीईआरटी Chemistry Part 1 and 2 [English] Class 11
पाठ 7 Redox Reactions
EXERCISES | Q 8.23 | पृष्ठ २८२

संबंधित प्रश्‍न

Calculate the oxidation number of sulphur, chromium and nitrogen in H2SO5, `"Cr"_2"O"_7^(2-)` and `"NO"_3^-`. Suggest structure of these compounds. Count for the fallacy.


Balance the following redox reactions by ion-electron method:

  1. \[\ce{MnO-_4 (aq) + I– (aq) → MnO2 (s) + I2(s) (in basic medium)}\]
  2. \[\ce{MnO-_4 (aq) + SO2 (g) → Mn^{2+} (aq) + HSO-_4  (aq) (in acidic solution)}\]
  3. \[\ce{H2O2 (aq) + Fe^{2+} (aq) → Fe^{3+} (aq) + H2O (l) (in acidic solution)}\]
  4. \[\ce{Cr_2O^{2-}_7 + SO2(g) → Cr^{3+} (aq) + SO^{2-}_4 (aq) (in acidic solution)}\]

Justify that the following reaction is redox reaction; identify the species oxidized/reduced, which acts as an oxidant and which acts as a reductant.

\[\ce{2Cu2O_{(S)} + Cu2S_{(S)}->6Cu_{(S)} + SO2_{(g)}}\]


Balance the following reaction by oxidation number method.

\[\ce{Cr2O^2-_{7(aq)} + SO^2-_{3(aq)}->Cr^3+_{ (aq)} + SO^2-_{4(aq)}(acidic)}\]


Balance the following redox equation by half-reaction method.

\[\ce{Bi(OH)_{3(s)} + SnO^2-_{2(aq)}->SnO^2-_{3(aq)} + Bi^_{(s)}(basic)}\]


What is the change in oxidation number of Sulphur in following reaction?

\[\ce{MnO^-_{4(aq)} + SO^{2-}_{3(aq)} -> MnO^{2-}_{4(aq)} + SO^{2-}_{4(aq)}}\]


Identify the oxidising agent in the following reaction:

\[\ce{CH4_{(g)} + 2O2_{(g)} -> CO2_{(g)} + 2H2O_{(l)}}\]


Consider the reaction:

\[\ce{6 CO2(g) + 6H2O(l) → C6 H12O6(aq) + 6O2(g)}\]

Why it is more appropriate to write these reaction as:

\[\ce{6CO2(g) + 12H2O(l) → C6 H12O6(aq) + 6H2O(l) + 6O2(g)}\]

Also, suggest a technique to investigate the path of the redox reactions.


Write balanced chemical equation for the following reactions:

Permanganate ion \[\ce{(MnO^{-}4)}\] reacts with sulphur dioxide gas in acidic medium to produce \[\ce{Mn^{2+}}\] and hydrogen sulphate ion.


Write balanced chemical equation for the following reactions:

Dichlorine heptaoxide \[\ce{(Cl2O7)}\] in gaseous state combines with an aqueous solution of hydrogen peroxide in acidic medium to give chlorite ion \[\ce{(ClO^{-}2)}\] and oxygen gas. (Balance by ion-electron method)


Balance the following equations by the oxidation number method.

\[\ce{I2 + S2O^{2-}3 -> I- + S4O^{2-}6}\]


Balance the following equations by the oxidation number method.

\[\ce{MnO2 + C2O^{2-}4 -> Mn^{2+} + CO2}\]


Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them.

\[\ce{3HCl (aq) + HNO3 (aq) -> Cl2 (g) + NOCl (g) + 2H2O (l)}\]


Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them.

\[\ce{HgCl2 (aq) + 2KI (aq) -> HgI2 (s) + 2KCl (aq)}\]


Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them.

\[\ce{PCl3 (l) + 3H2O (l) -> 3HCl (aq) + H3PO3 (aq)}\]


Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them.

\[\ce{4NH3 (g) + 3O2 (g) -> 2N2 (g) + 6H2O (g)}\]


\[\ce{H2O2 -> 2H^+ + O2 + 2e^-}\]; E0 = −0.68 V.

This equation represents which of the following behaviour of H2O2?


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