Advertisements
Advertisements
Question
Balance the following equation in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the reducing agent.
\[\ce{Cl_2O_{7(g)} + H_2O_{2(aq)} -> ClO-_{2(aq)} + O_{2(g)} + H+_{(aq)}}\]
Advertisements
Solution
The oxidation number of Cl decreases from + 7 in Cl2O7 to + 3 in `"ClO"_2^-` and the oxidation number of O increases from – 1 in H2O2 to zero in O2. Hence, in this reaction, Cl2O7 is the oxidizing agent and H2O2 is the reducing agent.
Ion–electron method:
The oxidation half equation is:
\[\ce{H2 ^{-1}O_{2(g)} -> ^{0}O_{2(g)}}\]
The oxidation number is balanced by adding 2 electrons as:
\[\ce{H_2O_{2(aq)} -> O_{2(g)} + 2e-}\]
The charge is balanced by adding 2OH– ions as:
\[\ce{H_2O_{2(aq)} -> + 2OH-_{(aq)} -> O_{2(g)} + 2e-}\]
The oxygen atoms are balanced by adding 2H2O as:
\[\ce{H_2O_{2(aq)} + 2OH-_{(aq)} -> O_{2(g)} + 2H_2O_{(l)} + 2e-}\] ....(i)
The reduction half equation is:
\[\ce{^{+7}Cl2O_{7(g)} -> ^{+3}ClO-_{2(aq)}}\]
The Cl atoms are balanced as:
\[\ce{Cl2O_{7(g)} -> 2ClO-_{2(aq)}}\]
The oxidation number is balanced by adding 8 electrons as:
\[\ce{Cl2O_{7(g)} + 8e- -> 2ClO-_{2(aq)}}\]
The charge is balanced by adding 6OH– as:
\[\ce{Cl_2O_{7(g)} + 8e- -> 2ClO-_{2(aq)} + 6OH-_{(aq)}}\]
The oxygen atoms are balanced by adding 3H2O as:
\[\ce{Cl_2O_{7(g)} + 3H_2O_{(l)} 8e- -> 2ClO-_{2(aq)} + 6OH-_{(aq)}}\] (ii)
The balanced equation can be obtained by multiplying equation (i) with 4 and adding equation (ii) to it as:
\[\ce{Cl_2O_{7(g)} + 4H_2O_{2(aq)} + 2OH-_{aq)} -> 2ClO-_{2(aq)} + 4O_{2(g)} + 5H_2O_{(l)}}\]
Oxidation number method:
Total decrease in oxidation number of Cl2O7 = 4 × 2 = 8
Total increase in oxidation number of H2O2 = 2 × 1 = 2
By multiplying H2O2 and O2 with 4 to balance the increase and decrease in the oxidation number, we get:
\[\ce{Cl_2O_{7(g)} + 4H_2O_{2(aq)} -> ClO-_{2(aq)} + 4O_{2(g)}}\]
The Cl atoms are balanced as:
\[\ce{Cl_2O_{7(g)} + 4H_2O_{2(aq)} -> 2ClO-_{2(aq)}+ 4O_{2(g)}}\]
The O atoms are balanced by adding 3H2O as:
\[\ce{Cl_2O_{7(g)} + 4H_2O_{2(aq)} -> 2ClO-_{2(aq)} + 4O_{2(g)} + 3H_2O_{(l)}}\]
The H atoms are balanced by adding 2OH– and 2H2O as:
\[\ce{Cl_2O_{7(g)} + 4H_2O_{2(aq)} + 2OH-_{(aq)} -> 2ClO-_{2(aq)} + 4O_{2(g)} + 5H_2O_{(l)}}\]
This is the required balanced equation.
APPEARS IN
RELATED QUESTIONS
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.
Whenever a reaction between an oxidising agent and a reducing agent is carried out, a compound of lower oxidation state is formed if the reducing agent is in excess and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations.
The Mn3+ ion is unstable in solution and undergoes disproportionation to give Mn2+, MnO2, and H+ ion. Write a balanced ionic equation for the reaction.
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.
In Ostwald’s process for the manufacture of nitric acid, the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum weight of nitric oxide that can be obtained starting only with 10.00 g. of ammonia and 20.00 g of oxygen?
Choose the correct option.
For the following redox reactions, find the correct statement.
\[\ce{Sn^{2⊕} + 2Fe^{3⊕}->Sn^{4⊕} + 2Fe^{2⊕}}\]
Balance the following reaction by oxidation number method.
\[\ce{Bi(OH)_{3(s)} + Sn(OH)^-_{3(aq)}->Bi_{(s)} + Sn(OH)^2-_{6(aq)}(basic)}\]
Balance the following redox equation by half-reaction method.
\[\ce{Bi(OH)_{3(s)} + SnO^2-_{2(aq)}->SnO^2-_{3(aq)} + Bi^_{(s)}(basic)}\]
Which of the following is INCORRECT for the following reaction?
\[\ce{2Zn_{(s)} + O2_{(g)} -> 2ZnO_{(s)}}\]
Identify the oxidising agent in the following reaction:
\[\ce{CH4_{(g)} + 2O2_{(g)} -> CO2_{(g)} + 2H2O_{(l)}}\]
When methane is burnt completely, oxidation state of carbon changes from ______.
Write balanced chemical equation for the following reactions:
Reaction of liquid hydrazine \[\ce{(N2H4)}\] with chlorate ion \[\ce{(ClO^{-}3)}\] in basic medium produces nitric oxide gas and chloride ion in gaseous state.
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.
\[\ce{Fe2O3 (s) + 3CO (g) ->[Δ] 2Fe (s) + 3CO2 (g)}\]
Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them.
\[\ce{4NH3 (g) + 3O2 (g) -> 2N2 (g) + 6H2O (g)}\]
The weight of CO is required to form Re2(CO)10 will be ______ g, from 2.50 g of Re2O7 according to given reaction
\[\ce{Re2O7 + CO -> Re2(CO)10 + CO2}\]
Atomic weight of Re = 186.2; C = 12 and O = 16.
\[\ce{H2O2 -> 2H^+ + O2 + 2e^-}\]; E0 = −0.68 V.
This equation represents which of the following behaviour of H2O2?
On balancing the given redox reaction,
\[\ce{aCr2O7^2- + Bso3^2- (aq) + CH+ (aq) -> 2aCr^3+ (aq) + bSO4^2- (aq) + c(H2O(1)/2}\]
the coefficients a, b and c are found to be, respectively:
