A2 Electrochemistry Flashcards
redox reaction
the transfer of electrons
the flow of electrons
is electrical current
oxidation
electrons are lost
reduction
electrons are gained
what happens in half cells
electrons flow between half cells.
what do half cells have
two different elements in different oxidation states
electrode
the part of the cell where electrons flow in and out from
what happens during oxidation
metal oxidises and ions are reduced
half cell equation direction
it shows a reduction reaction where an ion forms a metal
how can be gas be used in a redox electrochemical experiment?
the gas is bubble in the solution. the electrode used is platinum
why is a metal electrode used for gases?
to give it a surface to react on
why use platinum
it is inert
it is solid
it can conduct electricity
explain what happens in a gas one
chlorine gas passes through a glass tube
the glass tube is at 100kpa and 298k and 1 mol
there are cl-.
the chlorine ions are oxidised and chlorine gas is reduced,
it is a dynamic equilibrium as the forward and backwards reaction are at the same rate and constant concentration,
metal electrodes
metals surrounded by its solution
gas electrodes
gas in its aqeous solution
Redox electrode
two different ions of the same elements
how to measure the potential of an electrode
the actual potential of the cell cannot be measured directly.
add another half cell with known potential, measure the potential difference and subtract from known potential
electrochemical cell
two half cells
SHE
standard hydrogen electrode potential difference of 0 acts as a universal reference .
the standard which we compare the other potentials to.
how to set up electrochemical cell
- The metals are joined by a wire
- a piece of paper soack in concentrated kno3 is dipped in the solution to form a salt bridge
3, voltmeter
salt bridge
paper soaked in unreactive ions
agar
why use a high restitance voltmeter
to measure how hard electronsa re being pushed
to measure the potential of the electron flow
standard electron potential
the emf that is generated when connected to a standard hydrogen electrode in 298k, 100kpa and 1 mol dm-3
emf
how much force electrons are pushed asround the circuit
reducing cell
cathode
oxidising cell
anode
what way to electrons slow
negative to postitive - there is a force of attraction
