Ch.18 - ElectrochemistryWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Balancing Oxidation-Reduction Reactions

Concept #1: Balancing Redox Reactions

Concept #2: Balancing Acidic Redox Reactions

Practice: Balance the following reaction in an acidic solution. 

Cl2(g) + S2O32-(aq) ---->  Cl-(aq) + SO42-(aq) 

Concept #3: Balancing Basic Redox Reactions

Practice: Balance the following reaction in a basic solution. 

XeO2 (aq) ---->      H2Xe (aq)     +    XeO4 (aq)

Additional Problems
Balance the following redox reaction occurring in acidic solution. (Hint: the Br2 partakes in both half reactions) Br2 (l) → BrO3 (aq) + Br –(aq) 
Balance the following redox reaction in acidic conditions, listing the half reactions for oxidation and reduction. Also list the oxidation states of atoms in reaction.
Balance this ionic equation for a redox reaction, using only whole number coefficients.      ? MnO4- (aq) + ? Fe2+ (aq) + H3O+ (aq) → ? Mn2+ (aq) + ? Fe3+ (aq) + ? H2O (l) What is the coefficient for Fe2+ in the balanced equation? (A) 1 (B) 3 (C) 4 (D) 5
Complete and balance the following equations, and identify the oxidizing and reducing agents.MnO4-(aq) + CH3OH(aq)  →  Mn2+(aq) + HCO2H(aq)  (acidic  solution)
Complete and balance the following equations, and identify the oxidizing and reducing agents.As2O3(s) + NO3-(aq)  →  H3AsO4(aq) + N2O3(aq)  (acidic  solution)
Balance the redox reactions by following the steps in the text.CH3OH(l) + O2(g)  →  CO2(g) + H2O(l) (acidic)
Complete and balance the following equations, and identify the oxidizing and reducing agents.Pb(OH)42-(aq) + ClO-(aq)  →  PbO2(s) + Cl-(aq)  (basic  solution)
Design a voltaic cell from the following half-reactions:     Cr2O7(aq) + 14 H+(aq) + 6 e − → 2 Cr3+(aq) + 7 H2O(l)         E° = 1.33     O2(g) + 4 H+(aq) + 4 e − → H2O(l)                                          E° = 1.23In the overall reaction, how many H + ions would be shown and which side would they be on?A.  18 on the leftB.  16 on the leftC.  10 on the leftD.  10 on the rightE.  12 on the right
Determine whether or not each metal dissolves in 1 M HCl. For those metals that do dissolve, write a balanced redox reaction showing what happens when the metal dissolves.a. Cub. Fec. Au
Determine whether or not each metal dissolves in 1 M HIO 3. For those metals that do dissolve, write a balanced redox equation for the reaction that occurs.a. Aub. Cr
Balance the following equation in basic conditions. Phases are optional.SO32- + Co(OH)2 → Co + SO42-
For each of the following balanced oxidation-reduction reactions, (i) identify the oxidation numbers for all the elements in the reactants and products and (ii) state the total number of electrons transferred in each reaction.(a) I2O5(s) + 5 CO(g) → I2(s) + 5 CO2(g)
Use the half-reaction method to balance the equation for the conversion of ethanol to acetic acid in acid solution: CH3CH2OH + Cr2O72− ⟶ CH3COOH + Cr3+
The blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with an acidic potassium dichromate solution, resulting in the production of Cr3+(aq) and carbon dioxide. The reaction can be monitored because the dichromate ion (Cr2O72-) is orange in solution, and the Cr3+ ion is green. The unbalanced redox equation isCr2O72- (aq) + C2H5OH (aq) → Cr 3+ (aq) + CO2 (g)If 31.05 mL of 0.0600 M potassium dichromate solution is required to titrate 30.0 g blood plasma, determine the mass percent of alcohol in the blood.
If you complete and balance the following equation in acidic solutionMn2+(aq) + NaBiO3(s)  →  Bi3+(aq) + MnO4-(aq) + Na+(aq)how many water molecules are there in the balanced equation (for the reaction balanced with the smallest whole-number coefficients)?
Chlorine gas was first prepared in 1774 by C. W. Scheele by oxidizing sodium chloride with manganese(IV) oxide. The reaction isNaCl (aq) + H2SO4 (aq) + MnO2 (s) → Na 2SO4 (aq) + MnCl 2 (aq) + H2O (l) + Cl 2 (g)Balance this equation.
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) MnO4−(aq) + H2O2(aq) ⟶ Mn2+(aq) + O2(g) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) O2(g) + NO(g) ⟶ NO3−(aq) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) CrO42−(aq) + N2O(g) ⟶ Cr3+(aq) + NO(g) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) As4O6(s) + MnO4−(aq) ⟶ AsO43−(aq) + Mn2+(aq) [acidic]
Balance each of the following redox reactions occurring in acidic solution.SO32–(aq) + MnO4–(aq) → SO42–(aq) + Mn2+(aq)
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) MnO4−(aq) + HCOOH(aq) ⟶ Mn2+(aq) + CO2(g) [acidic]
In acidic solution, O3 and Mn2+ ions react spontaneously:O3(g) + Mn2+(aq) + H2O(l) ⟶ O2(g) + MnO2(s) + 2H+(aq)        E°cell = 0.84 V(a) Write the balanced half-reactions.
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.b. As2O3 (s) + NO3- (aq) → H3AsO4 (aq) + NO (g)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.d. CH3OH (aq) + Cr 2O72- (aq) → CH 2O (aq) + Cr 3+ (aq)
Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.)You may want to reference (Pages 852 - 857)Section 20.2 while completing this problem.Complete and balance the following equation:NO2-(aq) + Cr2O72-(aq)  →  Cr3+(aq) + NO3-(aq) (acidic solution)
Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.)You may want to reference (Pages 852 - 857)Section 20.2 while completing this problem.Complete and balance the following equation:Cr2O72-(aq) + CH3OH(aq)  →  HCO2H(aq) + Cr3+(aq) (acidic solution)
When a clean iron nail is placed in an aqueous solution of copper(II) sulfate, the nail becomes coated with a brownish-black material.(d) Write the balanced equation for the reaction.
Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states areAu+ ( aq ) + e-  →  Au ( s )          Eredo= + 1.69 VAu3 +  ( aq ) + 3e-  →  Au( s )      Eredo= + 1.50 VMiners obtain gold by soaking gold-containing ores in an aqueous solution of sodium cyanide. A very soluble complex ion of gold forms in the aqueous solution because of the redox reaction4 Au ( s ) + 8 NaCN ( aq ) + 2 H2O( l ) + O2 ( g )  →   4 Na[Au(CN)2]( aq ) + 4 NaOH ( aq )Gold miners then react the basic aqueous product solution from part C with Zn dust to get gold metal. Write a balanced redox reaction for this process.
Balance the redox reaction occurring in basic solution: ClO–(aq) + Cr(OH)4–(aq) → CrO42–(aq) + Cl–(aq)
Balance each of the following redox reactions occurring in basic solution.   a. H2O2(aq) + ClO2(aq) → ClO2-(aq) +O2(g) b. Al(s)+MnO4-(aq) → MnO2(s) + Al(OH)4-(aq) c. Cl2(g) → Cl−(aq)+ ClO−(aq)
Balance the following in basic solution:(a) SO3 2−(aq) + Cu(OH)2(s) ⟶ SO4 2−(aq) + Cu(OH)(s)
Balance the following in basic solution:(b) O2(g) + Mn(OH)2(s) ⟶ MnO2(s)
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) MnO4−(aq) + SO32−(aq) ⟶ MnO2(s) + SO42−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) AsO43−(aq) + NO2−(aq) ⟶ AsO2−(aq) + NO3−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) Fe(OH)2(s) + MnO4−(aq) ⟶ MnO2(s) + Fe(OH)3(s) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) Fe(OH)2(s) + Pb(OH)3−(aq) ⟶ Fe(OH)3(s) + Pb(s) [basic]
Balance each of the following redox reactions occurring in basic solution.H2O2(aq) + ClO2(aq) →  ClO2–( aq ) + O2(g)
In basic solution, Se2− and SO32− ions react spontaneously:2Se2−(aq) + 2SO32−(aq) + 3H2O(l) ⟶ 2Se(s) + 6OH−(aq) + S2O32−(aq)       E°cell = 0.35 V(a) Write balanced half-reactions for the process.
The overall cell reaction occurring in an alkaline battery isZn(s) + MnO2(s) + H2O(l) ⟶ ZnO(s) + Mn(OH)2(s)(a) How many moles of electrons flow per mole of reaction?
Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.)You may want to reference (Pages 852 - 857)Section 20.2 while completing this problem.Complete and balance the following equation:H2O2(aq) + ClO2(aq)  →  ClO2-(aq) + O2(g) (basic solution)
What is the coefficient of Fe2+ when the following reaction is balanced? Fe3+ + I– → Fe2+ + I2a. +4b. +3c. +2d. +5e. +1
What is the coefficient of Fe3+ when the following reaction is balanced? Bi 3+(aq) + Fe3+(aq) + H2O => BiO3 1- + Fe2+ + H+ (aq)a. 1b. 2c. 3d. 4e. 5
Balance the following reaction:NO2-(aq) + Cr2O72-(aq) → Cr3+(aq) + NO3-(aq)  (acidic solution)
Balance the following reaction:MnO4-(aq) + CH3OH(aq) → Mn2+(aq) + HCO2H(aq) (acidic solution)
Balance the following reaction:Cr2O72-(aq) + CH3OH(aq) ? HCO2H(aq) + Cr3+(aq) (acidic solution)
Balance the following redox reaction by inserting the appropriate coefficients.H+ + CrO42- + NO2- → Cr3+ + H2O +NO3-
Complete and balance the equation for this reaction in acidic solutionMnO4- + HNO2 → NO3- + Mn2+a) Which element got oxidized? reduced?b) Which species was the oxidizing agent? reducing agent?
If a nail made of elemental iron [Fe(s)] is placed in an aqueous solution of a soluble palladium(II) salt [Pd2+ (aq)], the nail will gradually disappear as the iron enters the solution as Fe3+ (aq) and palladium metal [Pd(s)] forms. a. Is this a redox equation? b. Balance and show the net ionic equation that describes this reaction.
In each reaction, find the oxidation number of each atom, label which species is oxidized and which is reduced, and label which species is the reducing agent and which is the oxidizing agent. SrSO4 + 4C → SrS + 4CO Oxidized: _____ Oxidizing Agent: _____ Reduced: _____ Reducing Agent: _____