Powerpoint Flashcards
electrochemistry
the branch of chemistry that examines the transformations between chemical and electrical energy
a reduction half reaction
a reactant gains electrons
an oxidation half reaction
a reactant loses electrons
reduction and oxidation half-reactions happen simultaneously
so the number of electrons gained during reduction must exactly match the number lost during oxidation
electrochemical cell
converts chemical energy into electrical work or electrical work into chemical energy
voltaic cell
chemical energy transformed into electrical energy by spontaneous redox reaction
electrodes
a bridge connects the two solutions of the cell, balances flow of electrons, eliminates accumulation of charge in either compartment
anode
electrode which oxidation half reaction takes place
cathode
electrode at which reduction half-reaction takes place
voltaic cell system
spontaneous cell reaction does work on its surroundings
electrolytic cell
external source of electrical power does work on system
standard reduction potential
the potential of a half reaction in which all reactants and products are their standard states
standard cell potential
a measure of how forcefully an electrochemical cell can pump electrons through an external circuit
where does the energy come from to pump electrons forcefully through an electrical circuit
these electrons can do electrical work and the ability for a chemical reaction to do work is expressed by the change in free energy, deltaG
when work is done on the surroundings…
w is less than zero, therefore, deltaG will be less than zero
as a spontaneous reaction proceeds, concentrations of products increases and concentrations of reactants decrease until
the positive value of RTlnQ offsets the negative value of deltaG. deltaG equals 0 and the reaction has reached equilibrium.
if K is less than 1,
reaction favors the reactants
if standard cell potential (Edegree cell) is less than 0,
reaction favors the reactants
if deltaGdegree cell is greater than 0,
reaction favors the reactants
if K is greater than 1,
the reaction favors the products
if standard cell potential (Edegree cell) is greater than 0,
the reaction favors the products
if deltaGdegree cell is less than 0,
the reaction favors the products
if K is equal to 1
the reaction favors formation of neither
if standard cell potential (Edegree cell) is equal to 0
the reaction favors formation of neither
