electrochemical cells Flashcards
what is a half cell
If a rod of metal is dipped into a solution of its own ions, an equilibrium is set up
Each part of the cell is called a half cell
what is an electrode potential
the electrode (reduction) potential (E) is a value which shows how easily a substance is reduced
if the electrode potential is more negative than it is less likely to undergo reduction ,equilibrium moves to the left
more postive electrode potentail ,equilibrium will move to the right
how is a cell represented
the half cell with the most negative potential goes on the left
the most oxidised species from each half cell ,is next to the salt bridge
what is the standard hydrogen electrode
0V measured under standard conditions
what are the standard conditions of a standard hydrogen electrode
solution of 1 mole conc
temperature -298k
100kpa -pressure
consists of hydrochloric acid, platinum electrode and hydrogen gas
-they are inert so they wont interfere with the reaction.
what does the cell potential mean
negative potential means cell will be likely to be oxidised
positive potential cell likely to be reduced
how do you find emf
right potential -left potential / most positive minus most negative
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how to find the most weakest/powerful oxidising agent
its always on the left hand side of the equation
its always the most positive
the weakest is the most negative
how do you find if reaction is feasible
take half equation of the most negative potential
flip it
combine half equation
find emf
if it is postive then it is feasibel
describe non-rechargeable batteries
cheaper
non reversible
describe components in a rechargeable battery
lithium ion batteries ,for example,
electrode A- lithium cobalt oxide
electrode B-graphite
electrolyte -lithium salt dissolved in organic solvent
what effect does increasing the pressure and concentration have on the EMF
increasing the concentration makes the cell more positive as fewer electrons are produced in the
increasing the pressure makes the EMF more negative
describe a fuel cell
A fuel cell uses the energy from the reaction of
a fuel with oxygen to create a voltage.
