Chemistry - Ch 20 Flashcards
Oxidizing agent (oxidant)
removes electrons from another substance by acquiring them itself
Electrochemistry
study of the relationships between electricity and chemical reactions
Reducing agent (reductant)
substance that gives up electrons, thereby causing another substance to be reduced
Half-reactions
equations that show either oxidation or reduction alone
Voltaic (galvanic) cell
device in which the transfer of electrons takes place through an external pathway rather than directly between reactants
anode
the electrode at which oxidation occurs
cathode
the electrode at which reduction occurs
Electromotive force (emf)
potential difference between the 2 electrons of a voltaic cel provides the driving force that pushes electrons through the external circuit
Cell potential
emf of a cell (Ecell)
Standard emf
standard cell potential
Standard Reduction Potentials
standard electrode potentials tabulated for reduction reactions
Standard hydrogen electrode (SHE)
electron designed to produce the reference half reaction (2H+ (aq, 1M) + 2e- –> H2 (gas, 1 atm)
faraday (F)
quantity of electrical charge on one mole of electrons
Nernst equation
equation that relates the cell emf, E, to the standard emf and the reaction quotient
Concentration cell
a cell based solely on the emf generated because of a difference in concentration
Battery
portable, self-contained electrochemical power source that consists of one or more voltaic cells
Fuel cells
voltaic cells that perform conversion of electricity from conventional fuels (H2, CH4)
Corrosion
spontaneous redox reactions in which a metal is attacked by some substance in its environment and converted to an unwanted compound
Cathodic protection
protecting a metal from corrosion by making it the cathode in an electrochemical cell
Electrolysis reactions
nonspontaneous redox reactions (driven by an outside source of electrical energy)
Electrolytic cells
where electrolysis reactions take place
Watt (w)
unit of electrical power (rate of energy expenditure)
