Chapter 21

Question 1

ampere (A)

Answer 1

the SI unit of electric current; 1 ampere of current results when 1 coulomb of charge flows through a conductor in 1 second

Question 2

anode

Answer 2

the electrode at which oxidation occurs in an electrochemical cell. Electrons are given up by the reducing agent and leave the cell at the anode

Question 3

battery

Answer 3

a group of voltaic cells arranged in series; primary and secondary types are self-contained, but flow batteries are not

Question 4

cathode

Answer 4

the electrode at which reduction occurs in an electrochemical cell. Electrons enter the cell and are acquired by the oxidizing agent at the cathode

Question 5

cell potential/voltage

Answer 5

the difference in electrical potential between the two electrodes of an electrochemical cell

Question 6

concentration cell

Answer 6

a voltaic cell in which both compartments contain the same components but at different concentrations

Question 7

corrosion

Answer 7

the natural redox process that results in unwanted oxidation of a metal

Question 8

coulomb (C)

Answer 8

the SI unit of electric charge. One coulomb is the charge of 6.242 × 1018 electrons; one electron possesses a charge of 1.602 × 10−19 C

Question 9

electrochemical cell

Answer 9

a system that incorporates a redox reaction to produce or use electrical energy

Question 10

electrochemistry

Answer 10

the study of the relationship between chemical change and electrical work

Question 11

electrode

Answer 11

the part of an electrochemical cell that conducts the electricity between the cell and the surroundings

Question 12

electrolysis

Answer 12

the nonspontaneous lysing (splitting) of a substance, often to its component elements, by the input of electrical energy

Question 13

electrolyte

Answer 13

a mixture of ions, in which the electrodes of an electrochemical cell are immersed, that conducts a current

Question 14

electrolytic cell/electromotive force (emf)

Answer 14

an electrochemical system that uses electrical energy to drive a nonspontaneous chemical reaction (ΔG > 0)

Question 15

Faraday constant (F)

Answer 15

the physical constant representing the charge of 1 mol of electrons: F = 96,485 C/mol e−

Question 16

fuel cell

Answer 16

a battery that is not self-contained and in which electricity is generated by the controlled oxidation of a fuel

Question 17

half-cell

Answer 17

a portion of an electrochemical cell in which a half-reaction takes place

Question 18

half-reaction method

Answer 18

a method of balancing redox reactions by treating the oxidation and reduction half-reactions separately

Question 19

Nernst equation

Answer 19

an equation stating that the voltage of an electrochemical cell under any conditions depends on the standard cell voltage and the concentrations of the cell components

Question 20

overvoltage

Answer 20

the additional voltage, usually associated with gaseous products forming at an electrode, that is required above the standard cell voltage to accomplish electrolysis

Question 21

salt bridge

Answer 21

an inverted U tube containing a solution of nonreacting ions that connects the compartments of a voltaic cell and maintains neutrality by allowing ions to flow between compartments

Question 22

standard cell potential

Answer 22

the potential of a cell measured with all components in their standard states and no current flowing

Question 23

standard electrode potential

Answer 23

the standard potential of a half-cell, with the half-reaction written as a reduction

Question 24

standard reference half-cell (SHE)

Answer 24

specially prepared platinum electrode immersed in 1 M H+(aq) through which H2 gas at 1 atm is bubbled. E half cell is defined as 0 V

Question 25

volt (V)

Answer 25

the SI unit of electrical potential: 1 V = 1 J/C

Question 26

voltaic (galvanic) cell

Answer 26

an electrochemical cell that uses a spontaneous redox reaction to generate electrical energy