oxidation
an increase in oxidation state (a loss of electrons)
reduction
a decrease in oxidation state (a gain of electrons)
oxidizing agent
a reactant that accepts electrons from another reactant
reducing agent
a reactant that donates electrons to another substance to reduce the oxidation state of one of its atoms
galvanic or voltaic cell
a device in which chemical energy is changed to electrical energy
salt bridge or porous disk
a u-tube containing an electrolyte that connects the two compartments of a galvanic cell, allowing ion flow without extensive mixing of different solutions
what's the purpose of the salt bridge in a galvanic cell?
cell potential. to maintain charge balance because electrons are moving from one half-cell to another
cell potential
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
anode
the electrode in a galvanic cell at which oxidation occurs
cathode
the electrode in a galvanic cell at which reduction occurs
which way do electrons flow in a cell?
electrons flow from anode to cathode in a cell
how do ions migrate from the salt bridge?
electrons flow from reducing agent to oxidizing agent. negative ions (anions) move toward the anode while positive ions (cations) move toward the cathode
why would KNO3 be a suitable salt for the salt bridge?
KNO3 won't make a solid. the substances in the compound are soluble and won't interrupt the reaction
what is an electrode?
a solid used to make contact with a nonconducting substance
which electrode increases in mass?
cathode
which electrode decreases in mass?
anode
what is line notation?
a shorthand way of expressing a certain reaction in an electrochemical cell