Balancing Redox Reactions

Redox Reactions 

While a normal chemical reaction involves balancing the atoms involved, a redox reaction involves balancing the number of electrons transferred between reactants. 

Concept: Balancing Redox Reactions

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Concept: Balancing Redox Reactions

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Concept: Balancing Redox Reactions

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Example: Balancing Redox Reactions

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Example: Balancing Redox Reactions

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Example: Balancing Redox Reactions

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Balancing Redox Reactions Additional Practice Problems

Balance the following half-reactions by adding the appropriate number of electrons. Which are oxidation half-reactions and which are reduction half-reactions ? 

Use the left and right arrow keys to move the cursor out of a superscript or subscript in the module. Add electrons by typing e- with the appropriate coefficient. For example, to add 2 electrons, type 2e- on the appropriate side of the equation. 

a. Fe2+ (aq) → Fe3+ (aq) 

b. AgI (s) → Ag (s) + I(aq) 

c. VO2+ (aq) + 2H+ (aq) → VO2+ (aq) + H2O (l) 

d. I2 (s) + 6H2O (l) → 2IO3- (aq) + 12H+ (aq) 

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Aluminum wire is placed in a copper (II) nitrate solution. Express your answer as a chemical equation. Identify all of the phases in your answer. Enter no reaction If there is no reaction.

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Complete and balance the equation for this reaction in acidic solution

MnO4- + HNO2 ---> NO3- + Mn2+

Which element got oxidized? reduced?

O, N, Mn

Which species was the oxidizing agent? reducing agent?

MnO4-, HNO2, H2O

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Balance the following redox reaction occurring in acidic aqueous solution.

Zn(s) + Sn 2+(aq) → Zn 2+(aq) + Sn(s)

Express your answer as a chemical equation. Identify all of the phases in your answer.

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In the process of oxidizing I - to I2, SO42- is reduced to SO2. How many moles of SO2 are produced in the formation of one mole of I 2?

Express your answer numerically in moles.

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Complete and balance the equation for this reaction in acidic solution.

ZnS + NO3- → Zn2+ + S + NO 

i) Which element got oxidized?

ii) Which element got reduced?

iii) Which species was the oxidizing agent?

iv) Which species was the reducing agent?

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For the oxidation-reduction reaction equation given here,

2Rb + Br2 → 2RbBr

Indicate how many electrons are transferred in the formation of one formula unit of product.

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Complete and balance the equation for this reaction in acidic solution.

MnO4+ HNO2 → NO3 + Mn2+

i) Which element got oxidized?

ii) Which element got reduce?

iii) Which species was the oxidizing agent?

iv) Which species was the reducing agent?

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Balance the following equation in basic conditions. Phases are optional.

N2H+ Cu(OH)2 → N+ Cu

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Balance the following equation in acidic conditions Phases are optional.

       S 2O3 2- + Cu 2+ → S4O6 2- + Cu+

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Balance the following equation in acidic conditions. Phases are optional.

C2O42- + MnO2 → Mn2+ + CO2

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Balance the following equation in acidic conditions. Phases are optional.

Cr2+ + H2MoO4 → Cr3+ + Mo

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Separate this redox reaction into its balanced component half-reactions.

Cl+ 2Na → 2NaCl

Oxidation of half reaction:


Reduction half reaction:

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Write a balanced overall reaction from these unbalanced half-reactions.

Sn → Sn2+

Ag+ → Ag

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Write a balanced overall reaction from these unbalanced half-reactions.

In → In3+

Cd2+ → Cd

 

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Write a balanced overall reaction from the unbalanced half-reaction.

Cu → Cu2+

Ag+ → Ag

 

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What is the coefficient of aluminum when the following reaction is balanced?

   Pt2+ + Al → Al 3+ + Pt

A) 1

B) 2

C) 3

D) 4

E) 6

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Write a balanced overall reaction from these unbalanced half-reactions. 

                                  Cu → Cu    2+ 

                                  Ag    + → Ag 

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Balance the following redox reaction in the order it is written:

___Fe + ___ I 2  →  ___ Fe 3+ + ___ I 

a. 1,1,1,2

b. 1,3,1,6

c. 3,3,3,6

d. 2,1,2,2

e. 2,3,2,6

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Consider the unbalanced redox reaction:
Cr2O72–(aq) + Cu(s) → Cr 3+ (aq) + Cu 2+(aq)
Balance the equation and determine the volume of a 0.850 M K2Cr2O7 solution required to completely react with 5.25 g of Cu.

 

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Consider the unbalanced redox reaction:

MnO4(aq) + Zn(s) → Mn2+(aq) + Zn2+(aq)

Balance the equation and determine the volume of a 0.500 M KMnO 4 solution required to completely react with 2.85 g of Zn.

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Balance the following reaction in acidic solution and determine the coefficient of H + and its location (reactant or product side) in the overall reaction.

HNO2 (aq) + HClO2 (aq) → N2O (aq) + ClO3 (aq)

a) 2, reactant

b) 4, reactant

c) 6, product

d) 4, product

e) 2, product

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What is the coefficient of the permanganate ion (MnO 4) when the following equation is balanced?

MnO4 + Br  → Mn2+ + Br2          (acidic solution)

A) 3                        B) 4                 C) 2                 D) 1                 E) 5

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