chapter 20 - electrochemistry Flashcards
oxidation
removing electrons from a material
reduction
adding electrons to a material
you cannot have…
oxidation without reduction
oxidizing agent
is reduced; causes another material to lose an electron
reducing agent
is oxidized, causes another material to gain an electron
OIL RIG
oxidation is losing, reduction is gaining
for an atom in its elemental form, the oxidation number is always…
zero
for any monoatomic ion, the oxidation number equals the
ionic charge
oxidation number 0
elemental form: H2, O2, F2
oxidation number +1
H (H2O, HBr, NH4)
oxidation number -2
O (H2O, CO2, SO42-)
oxidation number -1
O in peroxides (H2O2, NaO2)
oxidation number -1
F
red cat
reduction occurs at cathode
a positive cell potential (voltage) indicates a…
spontaneous electrochemical reaction
a negative cell potential (voltage) indicates a…
non-spontaneous reaction
anions travel towards the…
anode
cations travel towards the…
cathode
positive E cell corresponds to…
negative delta G, true for all redox reactions
for a spontaneous reaction (+E cell), K is…
“product favored”, significantly larger than 1
for a nonspontaneous reaction (-E cell), K is…
“reactant favored”, significantly lower than 1
voltaic (galvanic) cell
transfer of e occurs through external pathway; not directly between reactants in the reaction vessel
a _____ _______ is a way to transport excess anions from cathode to anode
salt bridge
electromotive force
joules/coulomb (J/C); another way to refer to Ecell
