Chapter 18 Flashcards
______ is the loss of electrons.
Oxidation
_____ is a gain of electrons.
Reduction
_____ corresponds to an increase in oxidation state (atom in products has less electrons than atom in reactants)
oxidation
_____ corresponds to an decrease in oxidation state (atom in products has more electrons than atom in reactants)
reduction
Define electrolysis
???
Define electrical current
the flow of electric charge
_____ reactions involve the transfer of electrons from one substance to another, they have the potential to generate electric current
redox
The generation of electricity through redox reactions is normally carried out in a device called an _____ _____
electrochemical cell
define electrochemical cell
???
define voltaic (or galvanic) cell
???
A voltaic (or galvanic) cell is and electrochemical cell that _____ electrical current from a _____ chemical reaction
produces
spontaneous
Define electrolytic cell
???
and electrolytic cell _____ electrical current to drive a ____ _____ reaction
consumes
non spontaneous
define half cell
???
define electrodes
conductive surfaces through which electrons can enter of leave half cells
what is electrical current measured in?
amperes (A)
define potential difference
the measure of the difference in potential energy (usually in joules) per unit of charge (coulombs)
what is the unit for potential difference
Volt (V)
what is potential difference also reffered to as?
emf (electromotive force)
____ is the potential difference between to electrodes in a voltaic cell
cell potential (Ecell)
or cell emf
What does the cell potential depend on?
the relative tendencies of the reactants to undergo oxidation and reduction
cell potential depends on the ______ of the reactants and products in the cell and the _____.
concentration
temperature
under standard conditions the cell potential is called the ___ ____ ____ (__)
standard cell potential (Eºcell)
The ___ ___ is a measure of the overall tendency of the redox reaction to occur spontaneously, the lower the cell potential, the _____ tendency to occur
cell potential
lower
the electrode where the oxidation occurs is the _____
anode
the electrode where the reduction occurs is the ____
cathode
_____ (anode or cathode?) is the source of electrons
anode
define salt bridge
????
a ___ ___ allows flow of ions that neutralizes the build up of charge in solution
???
define standard electrode potential
???
when the cells are connected, electrons flow spontaneously from the electrode with the ____ potential for oxidation to the electrode to the electrode with the ____ potential for reduction
higher
higher
define standard hydrogen electrode (SHE)
???
standard electrode potentials are always written in the form of _____ half reactions
reduction
_____ is the difference between the standard electrode potentials of the cathode and anode
Eºcell
Eºcell = _____ - ______
Eºcathode - Eºanode
The electrode potential of the standard hydrogen electrode (SHE) is exactly _____.`
zero
Eºcell is positive for _____ reactions
spontaneous
Eºcell is negative for _____ reactions
non-spontaneous
an oxidation-reduction reaction will proceed spontaneously in the direction that provides a _____ cell potential
positive
any reduction half reaction listed will be spontaneous when paired with the reverse half reaction that appears ______ it in the table.
below
The half reaction with the more positive electrode potential will undergo ____ (so substances at the top of the table are good _____ agents)
reduction
The half reaction with the more negative electrode potential will undergo ____ (so substances at the top of the table are good _____ agents)
oxidation
reducing
In general, metals whose reduction half reactions are listed ____ the reduction of H+ to H2 in the table will dissolve in acids, while metals listed ____ will not
below
above
HNO3 can oxidize metals that HCl cant like _____-
copper (copper is above H+ but not above NO3-)
define Farradays constant (F)
???
Farraday’s constant represents …?
the charge in coulombs per mole of electrons
what is n?
the number of electrons transferred in the reaction
