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

Batteries act as spontaneous electrochemical cells that help to generate electricity. 

Dry-Cell Batteries

These types of batteries get their names from the fact that they contain very little water. 

Concept #1: Dry-Cell Batteries

The overall reaction within a typical dry-cell battery is  

Zn (s) + 2 MnO2 (s) + 2 NH4+ (aq) → Zn2+ (aq) + Mn2O3 (s) + 2 NH3 (g) + H2O (l)

Alkaline Batteries

These types of batteries get their names from the fact that they operate within a basic medium. 

Concept #2: The counterpart to an acidic dry-cell battery is the alkaline battery. 

The overall reaction within a typical alkaline battery is  

Zn (s) + 2 MnO2 (s) + 2 H2O (l) → Zn(OH)2 (s) + 2 MnO(OH) (s)

Additional Problems
Heart pacemakers are often powered by lithium-silver chromate "button" batteries. The overall cell reaction is: 2Li(s) + Ag2CrO4(s)  →  Li2CrO4(s) + 2Ag(s)Lithium metal is the reactant at one of the electrodes of the battery. Is it the anode or the cathode?
Heart pacemakers are often powered by lithium-silver chromate "button" batteries. The overall cell reaction is: 2Li(s) + Ag2CrO4(s)  →  Li2CrO4(s) + 2Ag(s)The battery generates an emf of +3.5 V. How close is this value to the one calculated in part D?
Suppose that an alkaline battery was manufactured using cadmium metal rather than zinc. What effect would this have on the cell emf?
What environmental advantage is provided by the use of nickel-metal-hydride batteries over the nickel-cadmium batteries?
A 12-V automotive lead-acid battery. Each anode/cathode pair in this schematic cutaway produces a voltage of about 2 V. Six pairs of electrodes are connected in series, producing 12.What is the oxidation state of lead in the cathode of this battery?
Determine the optimum mass ratio of Zn to MnO2 in an alkaline battery.
The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp-hours (mAh). An "AA" alkaline battery yields a nominal capacity of 2850 mAh.What quantity of interest to the consumer is being expressed by the units of mAh?
The capacity of batteries such as the typical AA alkaline battery is expressed in units of milliamp-hours (mAh). An "AA" alkaline battery yields a nominal capacity of 2850 mAh.The starting voltage of a fresh alkaline battery is 1.55 V . The voltage decreases during discharge and is 0.85 V when the battery has delivered its rated capacity. If we assume that the voltage declines linearly as current is withdrawn, estimate the total maximum electrical work the battery could perform during discharge.
What voltage can theoretically be achieved in a battery in which lithium metal is oxidized and fluorine gas is reduced?
You may want to reference(Pages 263 - 267) Section 7.3 while completing this problem.Lithium is not nearly as abundant as sodium. If sodium ion batteries that function as lithium ion ones were developed, do you think sodium cobalt oxide would still work as the electrode material?
Explain how electrical current and potential difference differ.
Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries.Calculate the mass percent lithium in LiMn2O4?
Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries.1. Which material has a higher percentage of lithium? 2. Does this help to explain why batteries made with LiMn2O4 cathodes deliver less power on discharging?
Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries.In a battery that uses a LiCoO2 cathode approximately 50% of the lithium migrates from the cathode to the anode on charging. In a battery that uses a LiMn2O4 cathode what fraction of the lithium in LiMn2O4 would need to migrate out of the cathode to deliver the same amount of lithium to the graphite anode?
Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries.Calculate the mass percent lithium in LiCoO2?
Schematic of a Li-ion battery. When the battery is discharging (operating) Li+ ions move out of the anode and migrate through the electrolyte where they enter the spaces between the cobalt oxide layers, reducing the cobalt ions. To recharge the battery, electrical energy is used to drive the Li+ back to the anode, oxidizing the cobalt ions in the cathode.When a Li-ion battery is fully discharged the cathode has an empirical formula of LiCoO2. What is the oxidation number of cobalt in this state?
Schematic of a Li-ion battery. When the battery is discharging (operating) Li+ ions move out of the anode and migrate through the electrolyte where they enter the spaces between the cobalt oxide layers, reducing the cobalt ions. To recharge the battery, electrical energy is used to drive the Li+ back to the anode, oxidizing the cobalt ions in the cathode.Does the oxidation number of the cobalt increase or decrease as the battery charges?
Cutaway view of a miniature alkaline battery.What substance is oxidized as the battery discharges?
What are the anode and cathode reactions in a common dry-cell battery? In an alkaline battery?
What are the anode and cathode reactions in a lead-acid storage battery? What happens when the battery is recharged?
What are the three common types of portable rechargeable batteries and how does each one work?
What is a fuel cell? What is the most common type of fuel cell and what reactions occur at its anode and cathode?
Can the "fuel" of a fuel cell be a solid?
What is the difference between a battery and a fuel cell?
Which reaction is spontaneous in the hydrogen fuel cell: hydrogen gas plus oxygen gas makes water, or water makes hydrogen gas plus oxygen gas?
Many common electrical devices require the use of more than one battery.(a) How many alkaline batteries must be placed in series to light a flashlight with a 6.0-V bulb?
Many common electrical devices require the use of more than one battery.(b) What is the voltage requirement of a camera that uses six silver batteries?
The zinc-air battery is a less expensive alternative to silver batteries for use in hearing aids. The cell reaction is 2Zn(s) + O2(g) ⟶ 2ZnO(s)A new battery weighs 0.275 g. The zinc accounts for exactly 1/10 of the mass, and the oxygen does not contribute to the mass because it is supplied by the air.(a) How much electricity (in C) can the battery deliver?
Many common electrical devices require the use of more than one battery.(c) How many volts can a car battery deliver if two of its anode/cathode cells are shorted?
The zinc-air battery is a less expensive alternative to silver batteries for use in hearing aids. The cell reaction is 2Zn(s) + O2(g) ⟶ 2ZnO(s)A new battery weighs 0.275 g. The zinc accounts for exactly 1/10 of the mass, and the oxygen does not contribute to the mass because it is supplied by the air.(b) How much free energy (in J) is released if Ecell is 1.3 V?
What are the desirable qualities of an electric battery?
List some things that are typically considered when selecting a battery for a new application.
Consider a battery made from one half-cell that consist of a copper electrode in 1 M CuSO4 solution and another half-cell that consist of a lead electrode in 1 M Pb(NO  3)2 solution.(a) What are the reactions at the anode, cathode, and the overall reaction?
Why do batteries go dead, but fuel cells do not?
Explain what happens to battery voltage as a battery is used, in terms of the Nernst equation.
Using the information thus far in this chapter, explain why battery-powered electronics perform poorly in low temperatures.
A friend wants you to invest in his newly designed battery that produces 24 V in a single voltaic cell. Why should you be wary of investing in such a battery?
What voltage can theoretically be achieved in a battery in which lithium metal is oxidized and fluorine gas is reduced? Why might such a battery be difficult to produce?
Hydrogen gas has the potential as a clean fuel in reaction with oxygen. The relevant reaction is2H2 (g) + O2 (g)  →  2H2 O(l).Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a generator, much as coal is currently used in the electric power industry; (ii) hydrogen and oxygen gases are used to generate electricity directly by using fuel cells that operate at 85 oC.(a) Use data in Appendix C to calculate ΔH° and ΔS° for the reaction. We will assume that these values do not change appreciably with temperature. (b) Based on the values from part (a), what trend would you expect for the magnitude of ΔG for the reaction as the temperature increases? (c) What is the significance of the change in the magnitude of ΔG with temperature with respect to the utility of hydrogen as a fuel?Based on the analysis here, would it be more efficient to use the combustion method or the fuel-cell method to generate electrical energy from hydrogen?
You may want to reference(Pages 263 - 267) Section 7.3 while completing this problem.In a lithium-ion battery that is discharging to power a device, for every Li+ that inserts into the lithium cobalt oxide electrode, a Co4+ ion must be reduced to a Co3+ ion to balance charge. Will the lithium cobalt electrode expand or contract as lithium ions are inserted?
What reaction occurs at the anode of a lead storage battery?
Identify the battery that is used as a common flashlight battery.a) dry-cell batteryb) lithium ion batteryc) lead-acid storage batteryd) NiCad batterye) fuel cell