electrode potential and cells Flashcards
(37 cards)
what are the three type of cells
metal/metal ion
non metal/non metal
metal ion/metal ion
what is a half cell
compromises of an element in two oxidation states
what is in the simplest half cell
has a metal placed in an aqueous solution of its ions
where is the equilibrium
on the surface if the metal between the different oxidation state of the metals
how is the equilibrium written
in reduction form with the electrons always on the left
what happens if the equilibrium lies on the left
more electrons are released
more negative electrode
more oxidation
what happens if the equilibrium lies on the right
more electrons are gained
more reduction
more positive
how is e cell value calculated
obtained by comparing a cell to the standard hydrogen electrode she
what is the units for the e cell
volts
what is the she
it is a standard reference used as a comparison tool to compare potential to that of the she
what does the she have a potential of
o.oo v
describe the conditions of a standard hydrogen electrode
hydrogen gas bubbles
1mol/dm3
29k
100kpa
how is the platinum structured
coated with finely divided platinum which as a conducting surface
why is platinum used
it is unreactive and inert so doesn’t make a potential difference but also conducts electricity
what are properties of platinum
it is porous so it can absorb hydrogen gas
what exists on the surface of platinum
an equilibrium between hydrogen and hydrogen ions
why is standard conditions required
otherwise the position of redox equilibroium will change with conditions
how else can half cells be made
by two aqeous ions of the same element for example fe2+ and fe3+
what must be ensure
that the concentration of both ions are 1mol/dm
what is used as the conducting surface
platinum and metal surface
what is an electrochemical cell
it is formed from one half cell that releases electron and one half cell that gains electrons
what are connected to the half cells
a wire and a salt bridge
what does a wire allow
allows electrons to be transferred between the two half cells
what does the salt bridge provide
an electrical connection between the two solutionsq
