Question

Balancing Oxidation–Reduction Reactions (Section)

Complete and balance the following equations, and identify the oxidizing and reducing agents:

(a) Cr2O72-(aq) + I-(aq)→Cr3+(aq) + IO3-(aq) (acidic solution)

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(b) MnO4-(aq) + CH3OH(aq) →Mn2+(aq) +HCO2H(aq) (acidic solution)

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(c) I2(s) + OCl-(aq)→IO3-(aq) + Cl-(aq) (acidic solution)

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(d) As2O3(s) + NO3-(aq)→H3AsO4(aq) + N2O3(aq) (acidic solution)

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(e) MnO4-(aq) + Br-(aq)→MnO2(s) + BrO3-(aq) (basic solution)

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(f) Pb(OH)42-(aq) + ClO-(aq)→PbO2(s) + Cl-(aq) (basic solution)

Answer 1

(a)

Two half cell reactions

To balance the number of o-atoms by adding

To balance the number of H-atoms by adding

To balance the charge

Overall equation: -

By adding the above equation

(b)

Two half cell reactions

To balance the number of O-atoms by adding

To balance the number of H-atom by adding

To balance the charge: -

Multiplied equation (1) by 4 and (2) by 5

Overall equation by adding both of them

Change in oxidation state of

is an oxidizing agent as it is reduced thus is a reducing agent.

(c)

Two half cell reactions

To balance the number of O-atom by adding

To balance the number of H-atoms by adding

To balance the charge

Multiplied equation (2) by 5

Overall reaction by adding both the equation

Change in oxidation state of I and C1.

is oxidized thus it’s a reducing agent and is an oxidizing agent.

(d)

Two half cell reactions

To balance the number of O-atom by adding

To balance the number of H-atom by adding

To balance the charge: -

Overall reaction by adding the two reactions

Change in oxidation state of.

is oxidized thus it’s a reducing agent and is an oxidizing agent.

(e)

Two half cell reactions

To balance the number of O-atoms by adding

To balance the number of H-atoms by adding

To balance the charge: -

Multiplied equation and added to both sides of

the reaction

Overall reaction-:

Change in oxidation state of .

is reduced thus its an oxidizing agent and is the reducing agent.

(f)

Two half cell reactions

To balance the number of O-atom by adding

To balance the number of H-atom by adding-:

To balance the charge-:

Added the two equations: -

To neutralize ion, added to both sides-:

To determine the change in oxidation state-:

is oxidized thus it’s a reducing agent and is an oxidizing agent.