AP Chem Vocab - Chapter 18

electrochemistry

the study of the interchange of chemical and electrical energy

half-reactions

the two parts of an oxidation–reduction reaction, one representing oxidation, the other reduction

salt bridge

a U-tube containing an electrolyte that connects the two compartments of a galvanic cell, allowing ion flow without extensive mixing of the different solutions

porous disk

a disk in a tube connecting two different solutions in a galvanic cell that allows ion flow without extensive mixing of the solutions

galvanic cell

a device in which chemical energy from a spontaneous redox reaction is changed to electrical energy that can be used to do work

anode

the electrode in a galvanic cell at which oxidation occurs

cathode

the electrode in a galvanic cell at which reduction occurs

cell potential (electromotive force)

the driving force in a galvanic cell that pulls electrons from the reducing agent in one compartment to the oxidizing agent in the other

volt

the unit of electrical potential defined as one joule of work per coulomb of charge transferred

voltmeter

an instrument that measures cell potential by drawing electric current through a known resistance

standard hydrogen electrode

a platinum conductor in contact with 1 M H+ ions and bathed by hydrogen gas at one atmosphere

standard reduction potentials

the potential of a half-reaction under standard state conditions, as measured against the potential of the standard hydrogen electrode

faraday

a constant representing the charge on one mole of electrons; 96,485 coulombs

concentration cell

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

Nernst equation

an equation relating the potential of an electrochemical cell to the concentrations of the cell components: E= E° - (0.0591/n) log(Q) at 25°C

glass electrode

an electrode for measuring pH from the potential difference that develops when it is dipped into an aqueous solution containing H+ ions

ion-selective electrode

an electrode sensitive to the concentration of a particular ion in solution.

battery

a group of galvanic cells connected in series

lead storage battery

a battery (used in cars) in which the anode is lead, the cathode is lead coated with lead dioxide, and the electrolyte is a sulfuric acid solution

dry cell battery

a common battery used in calculators, watches, radios, and portable audio players

fuel cell

a galvanic cell for which the reactants are continuously supplied

corrosion

the process by which metals are oxidized in the atmosphere

galvanizing

a process in which steel is coated with zinc to prevent corrosion

cathodic protection

a method in which an active metal, such as magnesium, is connected to steel to protect it from corrosion

electrolytic cell

a cell that uses electrical energy to produce a chemical change that would otherwise not occur spontaneously

electrolysis

a process that involves forcing a current through a cell to cause a nonspontaneous chemical reaction to occur

ampere

the unit of electric current equal to one coulomb of charge per second

Downs cell

a cell used for electrolyzing molten sodium chloride

chlor-alkali process

the process for producing chlorine and sodium hydroxide by electrolyzing brine in a mercury cell