Physical Chemistry : Batteries
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Example Questions
Example Question #173 : Physical Chemistry
A battery converts __________ energy to __________ energy.
electrical . . . chemical
electrical . . . kinetic
chemical . . . kinetic
chemical . . . electrical
chemical . . . electrical
Electronic devices such as cell phones utilize batteries for power. A discharging battery converts the chemical energy associated with redox reactions to electrical energy that can be utilized to power the device. Kinetic energy is the energy associated with motion and is irrelevant to this question.
Example Question #1 : Batteries
Which of the following statements about a charging battery is true?
The battery behaves as a galvanic cell
Oxidation occurs at the cathode and reduction occurs at anode
The Gibbs free energy of the reaction in the battery is positive
The reaction occurring is exothermic
The Gibbs free energy of the reaction in the battery is positive
A charging battery behaves as an electrolytic cell. The process involves a nonspontaneous reaction; therefore, energy input is needed for charging a battery. This energy is provided by the electrical outlets that we use to charge our electronic devices, such as cell phones. Since it is nonspontaneous, the reaction occurring during charging has a positive Gibbs free energy.
Oxidation always occurs at the anode and reduction always occurs at the cathode, regardless of the type of cell. As mentioned previously, the charging battery requires energy input and behaves as an electrolytic cell. Exothermic reactions are characterized by a negative change in enthalpy. A reaction happening in an electrolytic cell is nonspontaneous. This means that the Gibbs free energy is always negative; however, other thermodynamic variables such as enthalpy and entropy can be either positive or negative.
Example Question #2 : Batteries
A charging battery is acting as a(n) __________ cell and a discharging battery is acting as a(n) __________ cell.
galvanic . . . galvanic
electrolytic . . . galvanic
galvanic . . . electrolytic
electrolytic . . . electrolytic
electrolytic . . . galvanic
A charging battery consumes energy from a power source like an electrical outlet, whereas a discharging battery releases energy and powers a device; therefore, a charging battery behaves as an electrolytic cell whereas a discharging battery behaves as a galvanic cell.
Example Question #3 : Batteries
Lithium batteries consist of lithium compounds and manganese dioxide. The reduction potential for lithium is 
I. Oxidation of manganese
II. Reduction of lithium
III. Oxidation of lithium
III only
I and II
I only
II and III
III only
A discharging battery behaves like a galvanic cell; therefore, it is characterized by a spontaneous reaction. This means that the reaction happening in a discharging battery has a positive standard reaction potential. Given the information in the question, we will get a positive standard reaction potential if the lithium atom is oxidized (half reaction potential = 
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