Question 1

The oxidation number of C in CH2Cl2 is ________. Hint: Assign oxidation numbers to hydrogen and chlorine first before determining carbon.

Accepted Answer

Question 2

The following unbalanced equation describes the production of metallic iron: Fe2O3 + C $\rarr$ Fe + CO2 What is the change in oxidation number for the carbon atom?

Accepted Answer

A) decreases by 1 
B) increases by 2 
C) increases by 3 
D) increases by 4 
E) decreases by 5 
A) decreases by 1 
B) increases by 2 
C) increases by 3 
D) increases by 4 
E) decreases by 5

Question 3

What is the oxidation number of each Cu atom in [Cu2Cl6]2-?

Accepted Answer

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

Question 4

A student will prepare a significant quantity of a gold compound which will be used in her research project, as well as other projects in her research group. The first step calls for the reaction of the gold metal with aqua regia (a 3:1 v/v mix of concentrated hydrochloric acid and concentrated nitric acid). In her procedure, she is to use 6 times as much aqua regia as the stoichiometric quantity required. A graduate student performed the calculation and indicated that aqua regia mixed according to directions has a nitrate concentration of 3.08 M and a chloride concentration of 6.96 M, while the hydrogen ion concentration is 10.04 M. The reaction is, Au(s)+ NO3-(aq)+ Cl-(aq)+ H+(aq)→ NO2(g)+ AuCl4-(aq)+ H2O(l) The piece of gold wire, that is, the starting material, weighs 9.562 grams. Calculate the volume, in mL, of aqua regia which is required, based on the consideration stated above. Hint: Balance your reaction and be sure to determine the limiting reagent.

Accepted Answer

Question 5

Nitrogen combines readily with molecular oxygen to form six known nitrogen oxides. The formulas of the nitrogen oxides in which nitrogen has an oxidation number of 4, are ________.

Accepted Answer

The answer of Nitrogen combines readily with molecular oxygen to...

Question 6

Which element would react most rapidly with water?

Accepted Answer

A) Ag 
B) K 
C) Cu 
D) Na 
E) Rb 
A) Ag 
B) K 
C) Cu 
D) Na 
E) Rb

Question 7

When the equation, Zn(s)+ NO3-(aq)→ NH4+(aq)+ Zn2+(aq)is balanced for an acidic solution, the sum of ALL the coefficients is ________. Hint: Do not neglect to include electrons when balancing redox reactions.

Accepted Answer

Question 8

After balancing the following equation for the reaction in basic media, 
I-(aq)+ MnO4-(aq)$\rarr$I2(aq)+ MnO2(s)what is the sum of ALL the coefficients in the equation? (Remember to include values of 1 in your summation.)Hint: Start by balancing each half-reaction.

Accepted Answer

A) 6 
B) 13 
C) 17 
D) 25 
E) 28 
A) 6 
B) 13 
C) 17 
D) 25 
E) 28

Question 9

Three metallic elements, copper, gold and zinc, can be distinguished from one another on the basis of how they react with two strong acids, HNO3(aq)and HCl(aq). Which set below, using the abbreviations R (for reaction occurs)and NR (for no reaction)correctly describes what occurs?

Accepted Answer

Question 10

The activity series of metals is Au < Ag < Cu < Sn < Cd < Zn < Al < Mg < Na < Cs Based on this list, which element below would undergo oxidation least readily?

Accepted Answer

A) Ag 
B) Al 
C) Cu 
D) Cd 
E) Zn 
A) Ag 
B) Al 
C) Cu 
D) Cd 
E) Zn

Question 11

The following unbalanced equation describes the production of metallic iron: Fe2O3 + C $\rarr$ Fe + CO2 Which is true?Hint: Remember the reducing agent is oxidized and the oxidizing agent is reduced.

Accepted Answer

A) Fe2O3 is the reducing agent, since it is reduced, while C is the oxidizing agent, since it oxidizes Fe2O3. 
B) Fe2O3 is the reducing agent, while Fe is the oxidizing agent, as it oxidizes C to CO2. 
C) Fe is the reducing agent, since it reduces C, while C is the oxidizing agent. 
D) Fe2O3 is the oxidizing agent, while C is the reducing agent, since it reduces Fe2O3. 
E) Fe2O3 is the reducing agent, while CO2 is the oxidizing agent. 
A) Fe2O3 is the reducing agent, since it is reduced, while C is the oxidizing agent, since it oxidizes Fe2O3. 
B) Fe2O3 is the reducing agent, while Fe is the oxidizing agent, as it oxidizes C to CO2. 
C) Fe is the reducing agent, since it reduces C, while C is the oxidizing agent. 
D) Fe2O3 is the oxidizing agent, while C is the reducing agent, since it reduces Fe2O3. 
E) Fe2O3 is the reducing agent, while CO2 is the oxidizing agent.

Question 12

The sulfite ion (SO32-)was involved in a chemical reaction in which it underwent oxidation. Based on the change in oxidation numbers, which of the species listed below is a possible oxidation product of the reaction?

Accepted Answer

A) S2O3 2-(aq) 
B) SO2(g) 
C) S2-(aq) 
D) S(s) 
E) SO42-(aq) 
A) S2O3 2-(aq) 
B) SO2(g) 
C) S2-(aq) 
D) S(s) 
E) SO42-(aq)

Question 13

Consider the following species: Cl2, Cl-, ClO-, ClO2-, ClO3-, and ClO4-. What is the oxidation number of Cl atom in each species, respectively?

Accepted Answer

A) (-1, +1, +1, +3, +5, +7) 
B) (0, +1, -1, -3, +5, +7) 
C) (0, -1, +1, +3, +5, +7) 
D) (0, +1, +1, +3, +5, +7) 
E) (-1, -1, +1, +3, +5, 0). 
A) (-1, +1, +1, +3, +5, +7) 
B) (0, +1, -1, -3, +5, +7) 
C) (0, -1, +1, +3, +5, +7) 
D) (0, +1, +1, +3, +5, +7) 
E) (-1, -1, +1, +3, +5, 0).

Question 14

All strong acids are also oxidizing acids.

Accepted Answer

A) True 
 B)False

Question 15

Balance the half-reaction, H2S $\rarr$ S8, taking place in acidic media. How many electrons are needed to balance the half-reaction?Hint: Remember the coefficients when balancing half-reactions, and look carefully at the oxidation numbers.

Accepted Answer

A) 12 electrons, left side 
B) 16 electrons, right side 
C) 14 electrons, left side 
D) 6 electrons, right side 
E) 8 electrons, right side 
A) 12 electrons, left side 
B) 16 electrons, right side 
C) 14 electrons, left side 
D) 6 electrons, right side 
E) 8 electrons, right side

Question 16

Which is the most likely reaction to reduce silver ions to silver metal? Hint: Silver metal refers to silver (Ag)in the solid phase.

Accepted Answer

A) 3Ag(s)+ Au3+(aq)$\rarr$3Ag+(aq)+ Au(s) 
B) Al(s)+ 3Ag+(aq)$\rarr$Al3+(aq)+ 3Ag(s) 
C) Hg(s)+ 2Ag+(aq)$\rarr$ Hg2+(aq)+ 2Ag(s) 
D) Au(s)+ 3Ag+(aq)$\rarr$ Au3+(aq)+ 3Ag(s) 
E) 2Ag(s)+ Hg2+(aq)$\rarr$2Ag+(aq)+ Hg(s) 
A) 3Ag(s)+ Au3+(aq)$\rarr$3Ag+(aq)+ Au(s) 
B) Al(s)+ 3Ag+(aq)$\rarr$Al3+(aq)+ 3Ag(s) 
C) Hg(s)+ 2Ag+(aq)$\rarr$ Hg2+(aq)+ 2Ag(s) 
D) Au(s)+ 3Ag+(aq)$\rarr$ Au3+(aq)+ 3Ag(s) 
E) 2Ag(s)+ Hg2+(aq)$\rarr$2Ag+(aq)+ Hg(s)

Question 17

In the equation, C4H10(l)+ Cr2O72-(aq) + H+(aq)$\rarr$ H6C4O4(s)+ Cr3+(aq)+ H2O(l), the change in the oxidation number of the chromium atom is

Accepted Answer

A) a decrease by six units. 
B) a decrease by three units. 
C) an increase by three units. 
D) an increase by five units. 
E) an increase by eight units. 
A) a decrease by six units. 
B) a decrease by three units. 
C) an increase by three units. 
D) an increase by five units. 
E) an increase by eight units.

Question 18

Organic compounds that contain the element ________ in their molecular structure require less oxygen than organic structures with similar masses in order to undergo complete combustion.

Accepted Answer

The answer of Organic compounds that contain the element ________...

Question 19

A partial activity series is: Au 2 3)2(aq); Fe(NO3)2(aq); HNO3(aq); Cu(NO3)2(aq); Sn(NO3)2(aq)? Hint: In the partial activity series above, Mn is the most reactive and Au is the least reactive.

Accepted Answer

A) Cd, Fe 
B) Cu, Cd 
C) Cu, Fe 
D) Fe, Sn 
E) Sn, Cu 
A) Cd, Fe 
B) Cu, Cd 
C) Cu, Fe 
D) Fe, Sn 
E) Sn, Cu

Question 20

Zinc reacts with the permanganate ion to form Zn2+(aq)ions and Mn2+(aq)ions. The reaction is:5 Zn(s)+ 2 MnO4-(aq)+ 16 H+ $\rarr$ 5 Zn2+(aq)+ 2 Mn2+(aq)+ 8 H2O How many grams of zinc are required to completely react with 100.0 mL of a 0.0150 M solution of KMnO4(aq)?

Accepted Answer

A) 0.0392 g 
B) 0.0981 g 
C) 0.245 g 
D) 10.2 g 
E) 43.9 g 
A) 0.0392 g 
B) 0.0981 g 
C) 0.245 g 
D) 10.2 g 
E) 43.9 g

Exam 6: Oxidation-Reduction Reactions

The oxidation number of C in CH2Cl2 is ________. Hint: Assign oxidation numbers to hydrogen and chlorine first before determining carbon.

The following unbalanced equation describes the production of metallic iron: Fe2O3 + C →\rarr→ Fe + CO2 What is the change in oxidation number for the carbon atom?

What is the oxidation number of each Cu atom in [Cu2Cl6]2-?

Nitrogen combines readily with molecular oxygen to form six known nitrogen oxides. The formulas of the nitrogen oxides in which nitrogen has an oxidation number of 4, are ________.

Which element would react most rapidly with water?

When the equation, Zn(s)+ NO3-(aq)→ NH4+(aq)+ Zn2+(aq)is balanced for an acidic solution, the sum of ALL the coefficients is ________. Hint: Do not neglect to include electrons when balancing redox reactions.

After balancing the following equation for the reaction in basic media, I-(aq)+ MnO4-(aq) →\rarr→ I2(aq)+ MnO2(s)what is the sum of ALL the coefficients in the equation? (Remember to include values of 1 in your summation.)Hint: Start by balancing each half-reaction.

Three metallic elements, copper, gold and zinc, can be distinguished from one another on the basis of how they react with two strong acids, HNO3(aq)and HCl(aq). Which set below, using the abbreviations R (for reaction occurs)and NR (for no reaction)correctly describes what occurs?

The activity series of metals is Au < Ag < Cu < Sn < Cd < Zn < Al < Mg < Na < Cs Based on this list, which element below would undergo oxidation least readily?

The following unbalanced equation describes the production of metallic iron: Fe2O3 + C →\rarr→ Fe + CO2 Which is true?Hint: Remember the reducing agent is oxidized and the oxidizing agent is reduced.

The sulfite ion (SO32-)was involved in a chemical reaction in which it underwent oxidation. Based on the change in oxidation numbers, which of the species listed below is a possible oxidation product of the reaction?

Consider the following species: Cl2, Cl-, ClO-, ClO2-, ClO3-, and ClO4-. What is the oxidation number of Cl atom in each species, respectively?

All strong acids are also oxidizing acids.

Balance the half-reaction, H2S →\rarr→ S8, taking place in acidic media. How many electrons are needed to balance the half-reaction?Hint: Remember the coefficients when balancing half-reactions, and look carefully at the oxidation numbers.

Which is the most likely reaction to reduce silver ions to silver metal? Hint: Silver metal refers to silver (Ag)in the solid phase.

In the equation, C4H10(l)+ Cr2O72-(aq) + H+(aq) →\rarr→ H6C4O4(s)+ Cr3+(aq)+ H2O(l), the change in the oxidation number of the chromium atom is

Organic compounds that contain the element ________ in their molecular structure require less oxygen than organic structures with similar masses in order to undergo complete combustion.

Zinc reacts with the permanganate ion to form Zn2+(aq)ions and Mn2+(aq)ions. The reaction is:5 Zn(s)+ 2 MnO4-(aq)+ 16 H+ →\rarr→ 5 Zn2+(aq)+ 2 Mn2+(aq)+ 8 H2O How many grams of zinc are required to completely react with 100.0 mL of a 0.0150 M solution of KMnO4(aq)?

A Very Brief History of Chemistry

Scientific Measurements

Elements, Compounds, and the Periodic Table

The Mole and Stoichiometry

Molecular View of Reactions in Aqueous Solutions

Energy and Chemical Change

The Quantum Mechanical Atom

The Basics of Chemical Bonding

Theories of Bonding and Structure

Properties of Gases

Intermolecular Attractions and the Properties of Liquids and Solids

Mixtures at the Molecular Level: Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases, a Molecular Look

Acid-Base Equilibria in Aqueous Solutions

Solubility and Simultaneous Equilibria

Thermodynamics

Electrochemistry

Nuclear Reactions and Their Role in Chemistry

Metal Complexes

Organic Compounds, Polymers, and Biochemicals

Filters

The oxidation number of C in CH₂Cl₂ is ________. Hint: Assign oxidation numbers to hydrogen and chlorine first before determining carbon.

The following unbalanced equation describes the production of metallic iron: Fe₂O₃ + C $\rarr$ Fe + CO₂ What is the change in oxidation number for the carbon atom?

What is the oxidation number of each Cu atom in [Cu₂Cl₆]^2-?

When the equation, Zn(s)+ NO₃^-(aq)→ NH₄⁺(aq)+ Zn²⁺(aq)is balanced for an acidic solution, the sum of ALL the coefficients is ________. Hint: Do not neglect to include electrons when balancing redox reactions.

After balancing the following equation for the reaction in basic media, I^-(aq)+ MnO₄^-(aq) $\rarr$ I₂(aq)+ MnO₂(s)what is the sum of ALL the coefficients in the equation? (Remember to include values of 1 in your summation.)Hint: Start by balancing each half-reaction.

Three metallic elements, copper, gold and zinc, can be distinguished from one another on the basis of how they react with two strong acids, HNO₃(aq)and HCl(aq). Which set below, using the abbreviations R (for reaction occurs)and NR (for no reaction)correctly describes what occurs?

The following unbalanced equation describes the production of metallic iron: Fe₂O₃ + C $\rarr$ Fe + CO₂ Which is true?Hint: Remember the reducing agent is oxidized and the oxidizing agent is reduced.

The sulfite ion (SO₃^2-)was involved in a chemical reaction in which it underwent oxidation. Based on the change in oxidation numbers, which of the species listed below is a possible oxidation product of the reaction?

Consider the following species: Cl₂, Cl^-, ClO^-, ClO₂^-, ClO₃^-, and ClO₄^-. What is the oxidation number of Cl atom in each species, respectively?

Balance the half-reaction, H₂S $\rarr$ S₈, taking place in acidic media. How many electrons are needed to balance the half-reaction?Hint: Remember the coefficients when balancing half-reactions, and look carefully at the oxidation numbers.

In the equation, C₄H₁₀(l)+ Cr₂O₇^2-(aq)+ H⁺(aq) $\rarr$ H₆C₄O₄(s)+ Cr³⁺(aq)+ H₂O(l), the change in the oxidation number of the chromium atom is

Zinc reacts with the permanganate ion to form Zn²⁺(aq)ions and Mn²⁺(aq)ions. The reaction is:5 Zn(s)+ 2 MnO₄^-(aq)+ 16 H⁺ $\rarr$ 5 Zn²⁺(aq)+ 2 Mn²⁺(aq)+ 8 H₂O How many grams of zinc are required to completely react with 100.0 mL of a 0.0150 M solution of KMnO₄(aq)?