Electrode Potentials and
Electrochemical Cells
, Electrode potentials
*A cell has two half-cells which have to be connected with a salt bridge. If the solutions are at 1.00moldm-3 an
*Simple half cells consist of a metal and a solution of a compound temperature at 298K, the potential differe
containing that metal. be 1.10V (standard electrode potential
*These two half cells produce an electric current that flows from the
more reactive metal to the less reactive metal. HALF CELLS
When a rod of metal is dipped into its ionic solut
*If the voltmeter is removed and replaced with a bulb, is formed, where two half cells can be joined tog
SALT BRIDGE electrical cell.
the circuit is short circuited and a current flows.
The salt bridge connects the circuit, transferring ions to Measuring potential would tell us how readily ele
*The reactions will then occur separately at each
complete the circuit. and how good a reducing agent i
electrode and the voltage will fall to zero as the reactants
It is made from a piece of filter paper soaked in a salt solution
are used up.
that is unreactive with the electrodes and electrode solutions E.g., The zinc half-cell has more of a tendency to
(usually saturated potassium nitrate) release electrons than copper. More electrons build
Cu2+(aq) + 2e- → Cu(s) POSITIVE
Wire is not used as it only transfers electrons and not ions and electrode and a potential difference is created whe
Zn(s) → Zn2+(aq) + 2e- NEGATIVE
would set up its own electrode system with the solutions negative terminal and copper is the positive termi
OVERALL: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
Electrochemical Cells
, Electrode potentials
*A cell has two half-cells which have to be connected with a salt bridge. If the solutions are at 1.00moldm-3 an
*Simple half cells consist of a metal and a solution of a compound temperature at 298K, the potential differe
containing that metal. be 1.10V (standard electrode potential
*These two half cells produce an electric current that flows from the
more reactive metal to the less reactive metal. HALF CELLS
When a rod of metal is dipped into its ionic solut
*If the voltmeter is removed and replaced with a bulb, is formed, where two half cells can be joined tog
SALT BRIDGE electrical cell.
the circuit is short circuited and a current flows.
The salt bridge connects the circuit, transferring ions to Measuring potential would tell us how readily ele
*The reactions will then occur separately at each
complete the circuit. and how good a reducing agent i
electrode and the voltage will fall to zero as the reactants
It is made from a piece of filter paper soaked in a salt solution
are used up.
that is unreactive with the electrodes and electrode solutions E.g., The zinc half-cell has more of a tendency to
(usually saturated potassium nitrate) release electrons than copper. More electrons build
Cu2+(aq) + 2e- → Cu(s) POSITIVE
Wire is not used as it only transfers electrons and not ions and electrode and a potential difference is created whe
Zn(s) → Zn2+(aq) + 2e- NEGATIVE
would set up its own electrode system with the solutions negative terminal and copper is the positive termi
OVERALL: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
