Ch.4 - Chemical Quantities & Aqueous ReactionsWorksheetSee 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
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 #1: Balancing Redox Reactions

Concept #2: Balancing Redox Reactions

Concept #3: Balancing Redox Reactions

Example #1: Balancing Redox Reactions

Example #2: Balancing Redox Reactions

Example #3: Balancing Redox Reactions

Additional Problems
Write a balanced overall reaction from these unbalanced half-reactions.                                    Cu → Cu    2+                                    Ag    + → Ag 
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
A sample of impure tin of mass 0.535 g is dissolved in strong acid to give a solution of Sn2+. The solution is then titrated with a 0.0448 M solution of NO 3-, which is reduced to NO(g). The equivalence point is reached upon the addition of 0.0344 L of the NO3- solution. Find the- percent by mass of tin in the original sample, assuming that it contains no other reducing agents.
Consider the reaction of 3.0 M dichromate: Cr2O7 2–      →       Cr3+ (Acidic Medium). What would be the coefficient on water in the balanced equation? a. 7 b. 5 c. 6 d. 4
Consider the equation: Cr2O7 2 – + H + + I –       →      Cr 3+ (aq) + H2O + I 3 – Which coefficient would be needed to balance I –? a) 9               b) 7               c) 5               d) 14
How many electrons are transferred in the following reaction after balancing? (The reaction is unbalanced!) Mg(s) + Al 3+(aq) → Al (s) + Mg2+(aq) A) 1 B) 2 C) 3 D) 4 E) 6
What is the coefficient of the oxidizing agent when it is balanced within a basic solution? Cl2(g) + S2O3 2- (aq)      →       Cl- (aq) + SO4 2- (aq)   a) 1                b) 2                c) 3                d) 4
When this oxidation-reduction equation is the balanced in acidic solution, using only whole number coefficients, what is the coefficient for S(s)?  ? Cr2O72- (aq) + ? H2S (aq) → ? Cr3+ (aq) + ? S (s) (A) 4 (B) 3 (C) 2 (D) 1
When the following redox equation is balanced with smallest whole-number coefficients, the coefficient for zinc will be. Zn(s) + ReO4-(aq) → Re(s) + Zn2+(aq) (acidic solution) A) 2 B) 7 C) 8 D) 16 E) None of these choices is correct.
Balance the following redox reaction if it occurs in basic solution. What are the coefficients in front of Br2 and OH- in the balanced reaction? Br2(l) → BrO3-(aq) + Br-(aq) A) Br2 = 3, OH - = 6 B) Br2 = 3, OH - = 3 C) Br2 = 2, OH - = 5 D) Br2 = 1, OH - = 2 E) Br2 = 1, OH - = 6
Balance each redox reaction occurring in acidic aqueous solution. a. Zn(s) + Sn2+(aq) → Zn2+(aq) + Sn(s)  
Balance each redox reaction occurring in acidic aqueous solution. b. Mg(s) + Cr3+(aq) → Mg2+(aq) + Cr(s)
Balance each redox reaction occurring in acidic aqueous solution. c. MnO4– (aq) + Al(s) → Mn 2+(aq) + Al 3+(aq)  
Balance each redox reaction occurring in acidic aqueous solution. a. I–(aq) + NO2– (aq) → I2(s) + NO(g)  
Balance each redox reaction occurring in acidic aqueous solution. b. ClO4–(aq) + Cl–(aq) → ClO3–(aq) + Cl2(g)
Balance each redox reaction occurring in acidic aqueous solution. c. NO3– (aq) + Sn2+(aq) → Sn4+(aq) + NO(g)  
Balance each redox reaction occurring in basic aqueous solution. b. Ag(s) + CN–(aq) + O2(g) → Ag(CN)2–(aq)
Balance each redox reaction occurring in basic aqueous solution. c. NO2– (aq) + Al(s) → NH3(g) + AIO2– (aq)
When concentrated H2SO4 (l) is added to I - (aq), I 2 (s) and H2S (g) are formed. When the equation for this reaction is balanced, what is the number of electrons transferred?   a) 8 b) 2 c) 4 d) 6 e) 1 
A disproportionation reaction is an oxidation-reduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions.Cl2(aq)  →  Cl-(aq) + ClO-(aq)  (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Sn2+(aq)  →  Sn4+(aq)   (acidic  or  basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.OH-(aq)  →  O2(g)   (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.SO32-(aq)  →  SO42-(aq)   (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.N2(g)  →  NH3(g)   (basic  solution)
Complete and balance the following equations, and identify the oxidizing and reducing agents.MnO4-(aq) + Br-(aq)  →  MnO2(s) + BrO3-(aq)  (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: Mn2+(aq)  →  MnO2(s)  (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: Cr ( OH )3(s)  →  CrO42-(aq)  (basic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: O2(g)  →  H2O(l)  (basic  solution)
A disproportionation reaction is an oxidation-reduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions.Ni+(aq)  →  Ni2+(aq) + Ni(s)  (acidic  solution)
A disproportionation reaction is an oxidation-reduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions.MnO42-(aq)  →  MnO4-(aq) + MnO2(s)  (acidic  solution)
A disproportionation reaction is an oxidation-reduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions.H2SO3(aq)  →  S(s) + HSO4-(aq)  (acidic  solution)
Uranium hexafluoride, UF6, is processed to produce fuel for nuclear reactors and nuclear weapons. UF6 is made from the reaction of elemental uranium with ClF3, which also produces Cl2 as a by-product. You may want to reference (Pages 149 - 153) Section 4.6 while completing this problem.Write the balanced molecular equation for the conversion of U and ClF3 into UF6 and Cl2.
Calcium carbonate, CaCO3, is often used as a dietary calcium supplement for bone health. Although CaCO3(s) is insoluble in water, it can be taken orally to allow for the delivery of Ca2+(aq) ions to the musculoskeletal system.Why is this the case? [Hint: Recall the reactions of metal carbonates discussed in Section 4.3 in the textbook.]
When magnesium metal is burned in air, two products are produced. One is magnesium oxide, MgO. The other is the product of the reaction of Mg with molecular nitrogen, magnesium nitride. When water is added to magnesium nitride, it reacts to form magnesium oxide and ammonia gas.Based on the charge of the nitride ion (-3), predict the formula of magnesium nitride.
When magnesium metal is burned in air, two products are produced. One is magnesium oxide, MgO. The other is the product of the reaction of Mg with molecular nitrogen, magnesium nitride. When water is added to magnesium nitride, it reacts to form magnesium oxide and ammonia gas.Write a balanced equation for the reaction of magnesium nitride with water.
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.TiO2(s)  →  Ti2+(aq)   (acidic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.ClO3-(aq)  →  Cl-(aq)   (acidic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.N2(g)  →  NH4+(aq)   (acidic  solution)
Complete and balance the following equations, and identify the oxidizing and reducing agents.Cr2O72-(aq) + I-(aq)  →  Cr3+(aq) + IO3-(aq)  (acidic  solution)
Complete and balance the following equations, and identify the oxidizing and reducing agents.I2(s) + OCl-(aq)  →  IO3-(aq) + Cl-(aq)  (acidic  solution)
Balance the redox reactions by following the steps in the text.I2(s) + Fe(s)  →  FeI2(s)
Balance the redox reactions by following the steps in the text.Cl2(g) + H2O2(aq)  →  Cl-(aq) + O2(g) (acidic)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: Mo3+(aq)  →  Mo(s)  (acidic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: H2SO3(aq)  →  SO42-(aq)  (acidic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: NO3-(aq)  →  NO(g) (acidic  solution)
Complete and balance the following half-reactions. In each case indicate whether the half-reaction is an oxidation or a reduction.Complete and balance the following half-reaction: O2(g)  →  H2O(l) (acidic  solution)
The discovery of hafnium, element number 72, provided a controversial episode in chemistry. G. Urbain, a French chemist, claimed in 1911 to have isolated an element number 72 from a sample of rare earth (elements 58-71) compounds. However, Niels Bohr believed that hafnium was more likely to be found along with zirconium than with the rare earths. D. Coster and G. von Hevesy, working in Bohrs laboratory in Copenhagen, showed in 1922 that element 72 was present in a sample of Norwegian zircon, an ore of zirconium. (The name hafnium comes from the Latin name for Copenhagen, Hafnia) .Zirconium, hafniums neighbor in group 4B, can be produced as a metal by reduction of solid ZrCl4 with molten sodium metal. Write a balanced chemical equation for the reaction.
Some metal oxides, such as Sc2O3, do not react with pure water, but they do react when the solution becomes either acidic or basic.Do you expect Sc2O3 to react when the solution becomes acidic or when it becomes basic?
How many electrons does each oxygen atom gain during the course of this reaction? Oxydation of calcium metal by molecular oxygen.
How many electrons are transferred in the following reaction? (The reaction is unbalanced.) Mg (s) + Al 3+(aq) → Al(s) + Mg 2+(aq)a. 6b. 2c. 3d. 1e. 4
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
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.
Separate this redox reaction into its balanced component half-reactions.Cl2 + 2Na → 2NaClOxidation of half reaction:Reduction half reaction:
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 the following redox reaction in the order it is written:___Fe + ___ I 2  →  ___ Fe 3+ + ___ I –a. 1,1,1,2b. 1,3,1,6c. 3,3,3,6d. 2,1,2,2e. 2,3,2,6
For the oxidation-reduction reaction equation given here,2Li + Se → Li 2SeIndicate how many electrons are transferred in the formation of one formula unit of product?
Balance the following oxidation–reduction reactions that occur in acidic solution.b. I-(aq) + ClO-(aq) → I3-(aq) + Cl-(aq) 
Balance the following oxidation–reduction reactions that occur in acidic solution.c. As2O3(s) + NO3-(aq) → H3AsO4(aq) + NO(g) 
Balance the following oxidation–reduction reactions that occur in acidic solution.d. Br-(aq) + MnO4-(aq) → Br2(l) + Mn2+(aq) 
Balance the following oxidation–reduction reactions that occur in acidic solution.e. CH3OH(aq) + Cr2O72-(aq) → CH2O(aq) + Cr3+(aq) 
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
Balance the following oxidation–reduction reactions that occur in basic solution.a. Cr(s) + CrO42-(aq) → Cr(OH)3(s)
Balance the following oxidation–reduction reactions that occur in basic solution.b. MnO4-(aq) + S2-(aq) → MnS(s) + S(s) 
Balance the following oxidation–reduction reactions that occur in basic solution.c. CN-(aq) + MnO4-(aq) → CNO-(aq) + MnO2(s) 
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?
Balance the following redox reaction by inserting the appropriate coefficients.SO42- + NH3 → SO32- + H2O + N2
Balance the following equation:Cu(s) + H+(aq) + NO3-(aq) → NO(g) + H2O(l) + Cu2+(aq)The coefficients are:A) 1,2,1,1,1,1B) 3,2,1,1,1,3C) 3,4,2,2,4,3D) 1,8,2,2,4,1E) 3,8,2,2,4,3
Consider the reaction at 55°C, where [Fe2+] = 3.80 M and [Mg2+] = 0.310 M Mg(s) + Fe2+(aq) → Mg+2(aq) + Fe(s)                      What is the value for n?
For the oxidation-reduction reaction equation given here,2K + F2 → 2KFindicate how many electrons are transferred in the formation of one formula unit of product.
For the oxidation-reduction reaction equation given below, indicate how many electrons are transferred in the formation of one formula unit of product.2Na + S → Na 2S 
Balance the following equation in acidic conditions. Phases are optional.H3AsO3+ I2 → H3AsO4 + I-(Redox and Oxidation Reactions)
Balance the following equation in acidic conditions. Phases are optional.Cr2+ + H2MoO4 + 4H+ → Cr3+ + Mo + 2H2O
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
For the oxidation-reduction reaction equation given here4Ga + P4 → 4GaPIndicate how many electrons are transferred in the formation of one formula of product.
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.
Balance the following redox reactions occurring in basic solution.MnO4−(aq) + Br -(aq) → MnO2(s) + BrO3−(aq)a. MnO4−(aq) + H2O(l) + Br−(aq) → MnO2(s) + 2OH−(aq) + BrO3−(aq)b. 2MnO4−(aq) +  H2O(l) + Br−(aq) → 2MnO2(s) + 2OH−(aq) + BrO3−(aq)c. 2MnO4−(aq) +  H2O(l) + Br−(aq) → 2MnO2(s) + OH−(aq) + BrO3−(aq)d. MnO4−(aq) +  H2O(l) + 2Br−(aq) → MnO2(s) + OH−(aq) + 2BrO3−(aq)
Balance the following redox reactions occurring in basic solution.NO2−(aq) + Al(s) → NH 3(g) + AlO2−(aq)a. NO2−(aq) + H2O(l) + 2Al(s) + OH−(aq) → NH3(g) + 2AlO2−(aq)b. NO2−(aq) + H2O(l) + 2Al(s) + OH−(aq) → 2NH3(g) + 2AlO2−(aq)c. NO2−(aq) + H2O(l) + Al(s) + 2OH−(aq) → 2NH3(g) + AlO2−(aq)d. NO2−(aq) + 2H2O(l) + Al(s) + 2OH−(aq) → NH3(g) + AlO2−(aq)
Balance each redox reaction occurring in basic aqueous solution.a. MnO4– (aq) + Br –(aq) → MnO2(s) + BrO3– (aq)
Write a balanced overall reaction from the unbalanced half-reaction. Cu → Cu2+ Ag+ → Ag  
Write a balanced overall reaction from these unbalanced half-reactions. In → In3+ Cd2+ → Cd  
Predict the formula for magnesium phosphide. What is the total number of electrons transferred?a. Mg2P3 ; 3 electrons are transferred from Mg to Pb. Mg3P2 ; 6 electrons are transferred from Mg to Pc. Mn3P ; 3 electrons are transferred from P to Mnd. MgP3 ; 6 electrons are transferred from Mg to Pe. MgP2 ; 4 electrons are transferred from P to Mg
Balance the following equation in basic conditions. Phases are optional. CoCl2 + Na2O2 → Co(OH)3 + Cl- + Na+
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.
Balance the following equation in acidic conditions. Phases are optional. C2O42- + MnO2 → Mn2+ + CO2
Balance the following equation in acidic conditions. Phases are optional. Cr2+ + H2MoO4 → Cr3+ + Mo
Balance each of the following equations according to the half-reaction method:(b) Zn(s) + NO3−(aq) ⟶ Zn2+(aq) + NH3(aq) (in base)
Balance each of the following equations according to the half-reaction method:(e) Cl2(g) + OH−(aq) ⟶ Cl−(aq) + ClO3−(aq) (in base)
Balance each of the following equations according to the half-reaction method:(g) NO2(g) ⟶ NO3−(aq) + NO2−(aq) (in base)
Balance each of the following equations according to the half-reaction method:(a) MnO4−(aq) + NO2−(aq) ⟶ MnO2(s) + NO3−(aq) (in base)
Balance each of the following equations according to the half-reaction method:(b) MnO42−(aq) ⟶ MnO4−(aq) + MnO2(s) (in base)
If you complete and balance the following oxidation-reduction reaction in basic solutionNO2-(aq) + Al(s)  →  NH3(aq) + Al(OH)4-(aq)how many hydroxide ions are there in the balanced equation (for the reaction balanced with the smallest whole-number coefficients)?
Balance the following oxidation–reduction reactions that occur in basic solution.a. Al (s) + MnO4- (aq) → MnO2 (s) + Al(OH)4- (aq)
Balance the following oxidation–reduction reactions that occur in basic solution.b. Cl2 (g) → Cl - (aq) + OCl - (aq)
Balance the following oxidation–reduction reactions that occur in basic solution.c. NO2- (aq) + Al (s) → NH 3 (g) + AlO2- (aq)
Balance the following oxidation–reduction reactions that occur in basic solution.a. Cr (s) + CrO42- (aq) → Cr(OH) 3 (s)
Balance the following oxidation–reduction reactions that occur in basic solution.b. MnO4- (aq) + S 2- (aq) → MnS (s) + S (s)
Balance the following oxidation–reduction reactions that occur in basic solution.c. CN - (aq) + MnO4- (aq) → CNO - (aq) + MnO2 (s)
Balance the following in basic solution:(c) NO3−(aq) + H2(g) ⟶ NO(g)
Balance the following in basic solution:(d) Al(s) + CrO42−(aq) ⟶ Al(OH)3(s) + Cr(OH)4−(aq)
Why is it not possible for hydrogen ion (H +) to appear in either of the half-reactions or the overall equation when balancing oxidation-reduction reactions in basic solution?
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) CrO42−(aq) + Cu(s) ⟶ Cr(OH) 3(s) + Cu(OH)2(s) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) BH4−(aq) + ClO3−(aq) ⟶ H2BO3−(aq) + Cl−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) Br2(l) ⟶ BrO3−(aq) + Br −(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) NO2(g) ⟶ NO3−(aq) + NO2−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) Zn(s) + NO3−(aq) ⟶ Zn(OH)42−(aq) + NH3(g) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) MnO4−(aq) + CN−(aq) ⟶ MnO2(s) + CNO−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) SO32−(aq) + Cl2(g) ⟶ SO42−(aq) + Cl−(aq) [basic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) Fe(CN)63−(aq) + Re(s) ⟶ Fe(CN)64−(aq) + ReO4−(aq) [basic]
Balance each of the following redox reactions occurring in basic solution.Al(s) + MnO4–(aq) →  MnO2(s) + Al(OH)4–(aq)
Balance each of the following redox reactions occurring in basic solution.Cl2(g) →  Cl–(aq) + ClO–(aq)
Balance each of the following redox reactions occurring in basic solution.MnO4–(aq) + Br–(aq) → MnO2(s) + BrO3–(aq)
Balance each of the following redox reactions occurring in basic solution.Ag(s) + CN–(aq) + O2(g) → Ag(CN)2–(aq)
Balance each of the following redox reactions occurring in basic solution.NO2–(aq) + Al(s) → NH3(g) + AlO2–(aq)
Balance the redox reactions by following the steps in the text.Hg2+(aq) + H2(g)  →  Hg(l) + H2O(l) (basic)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(d) H2(g) ⟶ H2O(l) (in basic solution)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(g) MnO2(s) ⟶ MnO4−(aq) (in basic solution)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(h) Cl−(aq) ⟶ ClO3−(aq) (in basic solution)
Balance each of the following equations according to the half-reaction method:(c) CN−(aq) + ClO2(aq) ⟶ CNO−(aq) + Cl−(aq) (in acid)
You may want to reference (Pages 850 - 851)Section 20.1 while completing this problem.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.(c) 3 H2S(aq) + 2 H+(aq) + 2NO3-(aq) → 3 S(s) + 2 NO(g) + 4 H2O(l)
Balance each of the following equations according to the half-reaction method:(d) Fe2+(aq) + Ce4+(aq) ⟶ Fe3+(aq) + Ce3+(aq)
Balance each of the following equations according to the half-reaction method:(a) Zn(s) + NO3−(aq) ⟶ Zn2+(aq) + N2(g) (in acid)
Balance each of the following equations according to the half-reaction method:(c) CuS(s) + NO3−(aq) ⟶ Cu2+(aq) + S(s) + NO(g) (in acid)
Balance each of the following equations according to the half-reaction method:(d) NH3(aq) + O2(g) ⟶ NO2(g) (gas phase)
Enter a balanced chemical equation for the reaction that occurs in each of the following cases.Cesium is added to water.
Enter a balanced chemical equation for the reaction that occurs in each of the following cases.Strontium is added to water.
Enter a balanced chemical equation for the reaction that occurs in each of the following cases.Sodium reacts with oxygen.
Enter a balanced chemical equation for the reaction that occurs in each of the following cases.Calcium reacts with iodine.
Balance each of the following equations according to the half-reaction method:(f) H2O2(aq) + MnO4−(aq) ⟶ Mn2+(aq) + O2(g) (in acid)
Balance each of the following equations according to the half-reaction method:(h) Fe3+(aq) + I−(aq) ⟶ Fe2+(aq) + I2(aq)
Balance each of the following equations according to the half-reaction method:(c) Br2(l) + SO2(g) ⟶ Br−(aq) + SO42−(aq) (in acid)
Consider the unbalanced redox reaction: MnO4–(aq) + Zn(s) → Mn2+(aq) + Zn2+(aq)Balance the equation.
Consider the unbalanced redox reaction: Cr2O72–(aq) + Cu(s) → Cr3+(aq) + Cu2+(aq)Balance the equation.
Balance each of the following redox reactions occurring in acidic aqueous solution.Zn(s) + Sn2+(aq) → Zn2+(aq) + Sn(s)
Balance each of the following redox reactions occurring in acidic aqueous solution.Mg(s) + Cr3+(aq) → Mg2+(aq) + Cr(s)
Balance each of the following redox reactions occurring in acidic aqueous solution.MnO4–(aq) + Al(s) → Mn2+(aq) + Al3+(aq)
Gold metal will not dissolve in either concentrated nitric acid or concentrated hydrochloric acid. It will dissolve, however, in aqua regia, a mixture of the two concentrated acids. The products of the reaction are the AuCl4- ion and gaseous NO. Write a balanced equation for the dissolution of gold in aqua regia.
Balance the following redox reaction in acidic solution: H+(aq) + Cr(s) → H2(g) + Cr2+(aq)
Balance the redox reaction equation (occurring in acidic solution) and choose the correct coefficients for each reactant and product.__VO2+(aq) + __Sn(s) + __H+(aq) → __VO2+(aq) + __Sn2+(aq) + __H2O(l)a) 2, 1, 4 → 2, 1, 2b) 1, 1, 2 → 1, 1, 1c) 2, 1, 2 → 2, 1, 1d) 2, 1, 2 → 2, 1, 2
Given the following pairs of balanced half-reactions, determine the balanced reaction for each pair of half reactions in an acidic solution. (a) Ca ⟶ Ca2+ + 2e−, F2 + 2e− ⟶ 2F− 
Given the following pairs of balanced half-reactions, determine the balanced reaction for each pair of half reactions in an acidic solution.(b) Li ⟶ Li+ + e−, Cl2 + 2e− ⟶ 2Cl− 
Balance the redox reaction in acidic solution: Cu(s) + NO3–(aq) → Cu2+(aq) + NO2(g)
Given the following pairs of balanced half-reactions, determine the balanced reaction for each pair of half reactions in an acidic solution.(c) Fe ⟶ Fe3+ + 3e−, Br2 + 2e− ⟶ 2Br− 
Given the following pairs of balanced half-reactions, determine the balanced reaction for each pair of half reactions in an acidic solution.(d) Ag ⟶ Ag+ + e−, MnO4 − + 4H+ + 3e− ⟶ MnO2 + 2H2O
Balance the following in acidic solution: (a) H2O2 + Sn2+ ⟶ H2O + Sn4+ 
Balance the following in acidic solution:(b) PbO2 + Hg ⟶ Hg22+ + Pb2+ 
Balance the following in acidic solution:(c) Al + Cr2O72− ⟶ Al3+ + Cr3+
Consider the following unbalanced oxidation-reduction reactions in aqueous solution:Ag+(aq) + Li(s) → Ag(s) + Li+(aq)Fe(s) + Na+(aq) → Fe2+(aq) + Na(s)K(s) + H2O(l) → KOH(aq) + H2(g)Balance the first reaction.
Consider the following unbalanced oxidation-reduction reactions in aqueous solution:Ag+(aq) + Li(s) → Ag(s) + Li+(aq)Fe(s) + Na+(aq) → Fe2+(aq) + Na(s)K(s) + H2O(l) → KOH(aq) + H2(g)Balance the second reaction.
Consider the following unbalanced oxidation-reduction reactions in aqueous solution:Ag+(aq) + Li(s) → Ag(s) + Li+(aq)Fe(s) + Na+(aq) → Fe2+(aq) + Na(s)K(s) + H2O(l) → KOH(aq) + H2(g)Balance the third reaction.
Consider the following balanced redox reaction:16H+ (aq) + 2MnO4− (aq) + 10Cl − (aq) ⟶ 2Mn 2+ (aq) + 5Cl 2 (g) + 8H2O (l)(f) Write the balanced molecular equation, with K + and SO42− as the spectator ions.
At 900oC titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride.Write a balanced equation for this reaction.
Hydrazine (N2H4) and dinitrogen tetroxide (N2O4) form a self-igniting mixture that has been used as a rocket propellant. The reaction products are N2 and H2O.Write a balanced chemical equation for this reaction.
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) ClO3−(aq) + I−(aq) ⟶ I2(s) + Cl−(aq) [acidic]
Why is it not possible for hydroxide ion (OH −) to appear in either of the half-reactions or the overall equation when balancing oxidation-reduction reactions in acidic solution?
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) Cr2O72−(aq) + Zn(s) ⟶ Zn2+(aq) + Cr3+(aq) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) Zn(s) + NO3−(aq) ⟶ Zn2+(aq) + N2(g) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(a) Sb(s) + NO3−(aq) ⟶ Sb4O6(s) + NO(g) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) Mn2+(aq) + BiO3−(aq) ⟶ MnO4−(aq) + Bi 3+(aq) [acidic]
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(c) H2S(g) + NO3−(aq) ⟶ S8(s) + NO(g) [acidic]
Balance each of the following redox reactions occurring in acidic aqueous solution.K(s) + Cr3+(aq) → Cr(s) + K+(aq)
Balance each of the following redox reactions occurring in acidic aqueous solution.Al(s) + Fe2+(aq) → Al3+(aq) + Fe(s)
Balance the following skeleton reactions and identify the oxidizing and reducing agents:(b) P4(s) ⟶ HPO32−(aq) + PH3(g) [acidic]
Balance each of the following redox reactions occurring in acidic aqueous solution.BrO3– (aq) + N2H4(g) → Br–(aq) + N2(g)
Balance each of the following redox reactions occurring in acidic solution.PbO2(s) + I–(aq) → Pb2+(aq) + I2(s)
Balance each of the following redox reactions occurring in acidic solution.S2O32–(aq) + Cl2(g) → SO42–(aq)+Cl–(aq)
Balance each of the following redox reactions occurring in acidic solution.I–(aq) + NO2–(aq) → I2(s) + NO(g)
In many residential water systems, the aqueous Fe 3+ concentration is high enough to stain sinks and turn drinking water light brown. The iron content is analyzed by first reducing the Fe3+ to Fe2+ and then titrating with MnO4− in acidic solution. Balance the skeleton reaction of the titration step:Fe2+(aq) + MnO4−(aq) ⟶ Mn2+(aq) + Fe3+(aq)
Balance each of the following redox reactions occurring in acidic solution.ClO4–(aq) + Cl–(aq) → ClO3–(aq) + Cl2(g)
Aqua regia, a mixture of concentrated HNO 3 and HCl, was developed by alchemists as a means to “dissolve” gold. The process is a redox reaction with this simplified skeleton reaction:Au(s) + NO3−(aq) + Cl−(aq) ⟶ AuCl4−(aq) + NO2(g)(a) Balance the reaction by the half-reaction method.
Balance each of the following redox reactions occurring in acidic solution.NO3–(aq) + Sn2+(aq) → Sn4+(aq) + NO(g)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(a) Cr2+(aq) ⟶ Cr3+(aq)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(c) ZnS(s) ⟶ Zn(s) + S2−(aq)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(e) H2(g) ⟶ H3O+(aq) (in acidic solution)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.a. I - (aq) + ClO - (aq) → I 3- (aq) + Cl - (aq)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.c. Br2 (aq) + MnO4- (aq) → Br 2 (l) + Mn 2+ (aq)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(f) NO3−(aq) ⟶ HNO2(aq) (in acidic solution)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.a. Cu (s) + NO3- (aq) → Cu 2+ (aq) + NO (g)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(a) Sn4+(aq) ⟶ Sn2+(aq)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.b. Cr2O72- (aq) + Cl - (aq) → Cr3+ (aq) + Cl 2 (g)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(h) Cl−(aq) ⟶ ClO3−(aq) (in acidic solution)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.c. Pb (s) + PbO2 (s) + H2SO4 (aq) → PbSO4 (s)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.d. Mn2+ (aq) + NaBiO3 (s) → Bi 3+ (aq) + MnO4- (aq)
Balance the following oxidation–reduction reactions that occur in acidic solution using the half-reaction method.e. H3AsO4 (aq) + Zn (s) → AsH 3 (g) + Zn2+ (aq)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(b) [Ag(NH3)2]+(aq) ⟶ Ag(s) + NH3(aq)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(c) Hg2Cl2(s) ⟶ Hg(l) + Cl−(aq)
The discovery of hafnium, element number 72, provided a controversial episode in chemistry. G. Urbain, a French chemist, claimed in 1911 to have isolated an element number 72 from a sample of rare earth (elements 58-71) compounds. However, Niels Bohr believed that hafnium was more likely to be found along with zirconium than with the rare earths. D. Coster and G. von Hevesy, working in Bohrs laboratory in Copenhagen, showed in 1922 that element 72 was present in a sample of Norwegian zircon, an ore of zirconium. (The name hafnium comes from the Latin name for Copenhagen, Hafnia) .Solid zirconium dioxide, ZrO2, is reacted with chlorine gas in the presence of carbon. The products of the reaction are ZrCl4 and two gases, CO2 and CO in the ratio 1:2. Write a balanced chemical equation for the reaction: ZrO2(s) + Cl2(g) + C(s) → ZrCl4(s) + CO2(g) + CO(g)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(d) H2O(l) ⟶ O2(g) (in acidic solution)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(e) IO3−(aq) ⟶ I2(s)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(f) SO32−(aq) ⟶ SO42−(aq) (in acidic solution)
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(g) MnO4−(aq) ⟶ Mn2+(aq) (in acidic solution)
Balance each of the following equations according to the half-reaction method:(a) Sn2+(aq) + Cu2+(aq) ⟶ Sn4+(aq) + Cu+(aq)
Some metal oxides, such as Sc2O3, do not react with pure water, but they do react when the solution becomes either acidic or basic.Write a balanced chemical equation to support your answer.
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.S(s) + HNO3(aq)  →  H2SO3(aq) + N2O(g) (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:BrO3-(aq) + N2H4(aq)  →  Br2(l) + N2(g) (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.NO2-(aq) + Al(s)  →  NH4+(aq) + AlO2-(aq) (acidic solution)
In addition to reacting with gold (see Problem 21.21), aqua regia is used to bring other precious metals into solution. Balance the skeleton equation for the reaction with Pt:Pt(s) + NO3−(aq) + Cl−(aq) ⟶ PtCl62−(aq) + NO(g)
Balance each of the following equations according to the half-reaction method:(b) H2S(g) + Hg22+(aq) ⟶ Hg(l) + S(s) (in acid)
You may want to reference (Pages 850 - 851)Section 20.1 while completing this problem.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.(b) 2Hg2+(aq) + N2H4(aq) → 2 Hg(l) + N2(g) + 4 H+(aq)
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.(c) Ba2+(aq) + 2 OH-(aq) + H2O2(aq) + ClO2(aq) → Ba(ClO2)2(s) + 2 H2O(l) + O2(g)
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.(b) 4 H2O2(aq) + Cl2O7(g) + 2 OH-(aq) → 2 ClO2-(aq) + 5 H2O(l) + 4 O2(g)
You may want to reference (Pages 850 - 851)Section 20.1 while completing this problem.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) 2 MnO4-(aq) + 3 S2-(aq) + 4 H2O(l) → 3 S(s) + 2MnO2(s) + 8 OH-(aq)
Balance the following redox reaction occurring in acidic solution. Express your answer as a chemical equation. Identify all of the phases in your answer.IO3-(aq) + H2SO3(aq) → I2(aq) + SO42-(aq)
Balance the following redox reaction occurring in acidic solution. Express your answer as a chemical equation. Identify all of the phases in your answer.NO3-(aq) + Sn2+(aq) → Sn4+(aq) + NO(g)
Balance the following redox reaction occurring in acidic solution. Express your answer as a chemical equation. Identify all of the phases in your answer.Cr2O72-(aq) + Cu+(aq) → Cr3+(aq) + Cu2+(aq)
Balance the following oxidation–reduction reactions that occur in acidic solution.a. Zn(s) + HCl(aq) → Zn2+(aq) + H2(g) + Cl-(aq)
Balance the following redox reaction by inserting the appropriate coefficients.HNO3 + H2S → NO + S + H2O
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. 
In acidic solution, the sulfate ion can be used to react with a number of metal ions. One such reaction isSO42- (aq) + Sn2+ (aq) → H2SO3 (aq) + Sn4+ (aq)Sicne this reaction takes place in acidic solution, H2O (l) and H+ (aq) will be involved in the reaction. Places for these species are indicated by the blanks in the following restatement of the equation:SO42- (aq) + Sn2+ (aq) + ___ → H2SO3 (aq) + Sn4+ (aq) + ___What are the coefficients of the reactants and products in the balaced equation above? Remember to include H2O (l) and H+ (aq) in the appropriate blanks. Your answer should have six terms.
Balance the following reaction:Pb(OH)42-(aq) + ClO ? (aq) ? PbO 2(s) + Cl ? (aq) (basic solution)
(1) Identify each of the following half-reactions as either an  oxidation half-reaction or a reduction half-reaction. (2) Write a balanced equation for the overall redox reaction.  Use smallest possible integer coefficients.
For the oxidation-reduction reaction equation given here,2Rb + Br2 → 2RbBrIndicate how many electrons are transferred in the formation of one formula unit of product.
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) 
When the following half reaction is balanced under acidic conditions, what are the coefficients of the species shown? H2SO3 + H2O → SO42- + H- In the above half reaction, the oxidation state of sulfur changes from ________ to ________ .
(1) Identify each of the following half-reactions as either an  oxidation half-reaction or a reduction half-reaction. (2) Write a balanced equation for the overall redox reaction.  Use smallest possible integer coefficients.
Balance the following equation in acidic conditions. Phases are optional.       S 2O3 2- + Cu 2+ → S4O6 2- + Cu+
Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):(b) Hg(l) + Br−(aq) ⟶ HgBr42−(aq)
Write a balanced half-reaction for the oxidation of solid iodine dioxide (IO2) to iodate ion (IO3-) in acidic aqueous solution. Be sure to odd physical state symbols where appropriate.
Balance the following equation in basic conditions. Phases are optional.CoCl2 + Na2O2 → Co(OH)3 + Cl- + Na+(redox and oxidation reactions) 
Balance the following equation in basic conditions. Phases are optional.N2H4 + Cu(OH)2 → N2 + Cu
Balance each of the following equations according to the half-reaction method:(e) HBrO(aq) ⟶ Br−(aq) + O2(g) (in acid)
Write a balanced overall reaction from these unbalanced half-reactions.Sn → Sn2+Ag+ → Ag
Balance the following redox reaction by inserting the appropriate coefficients.HNO3 + H2S → NO +S + H2O