23.4 Electrode potentials Flashcards
what does a voltaic cell do?
converts chemical energy to electrical energy
how do redox reactions generate electrical energy?
there is a transfer of electrons so electrical energy is formed
what is a half-cell?
contains chemical species required for a redox reaction
what is made when 2 half-cells are connected?
a voltaic cell
what would happen if the 2 half-cells were mixed?
the energy created would be heat energy not electrical energy
what are the 2 types of half-cells?
metal/metal ion
ion/ion
what is a metal/metal ion half-cell?
a metal rod dipped into a solution of it’s aqueous metal ion
what is the phase boundary?
the point where the aqueous metal ions come into contact with the metal rod
what is created at the phase boundary in a metal/metal ion half-cell?
an equilibirum
what is the forward reaction in the EQ formed?
reduction
what is the backward reaction in the EQ formed?
oxidation
what is an ion/ion half cell?
contains ions of the same element but in different oxidation states
an inert metal electrode is used to transfer electrons
(made of Pt)
which electrode is reduced?
the one with the more reactive metal
which electrode is oxidised?
the one with the less reactive metal
which electrode is the negative one?
the one which is oxidised
loses electrons
which electrode is the positive one?
the one which is reduced
gains electrons
what is the standard electrode potential?
the tendency for a species to be reduced and gain electrons
what is the standard used for standard electrode potential?
half-cell with H2 gas and an acid solution with a Pt electrode
what is the standard electrode potential of a hydrogen half-cell?
0V
how is standard electrode potential measured?
the half-cell being measured is connected to a hydrogen half-cell by a wire
they are also connected by a salt bridge which allows for ions to flow
what is a salt bridge made out of?
filter paper soaked in electrolyte
the more negative the E⊖
greater the tendency to lose electrons and be oxidised
the more positive the E⊖
greater the tendency to
the more negative the E⊖
the greater the tendency to LOSE electrons and undergo oxidation
the more positive the E⊖
the greater the tendency to GAIN electrons and undergo reduction
how is the standard cell potential calculated?
E⊖ (reduced) - E⊖ (oxidised)
what are the charge carriers in the wires?
electrons
what are the charge carriers in salt bridge?
ions
