Electrochemical Series
A list of electrode potentials for different electrochemical half cells.
More positive electrode - left hand substances are more easily reduced. Right
handed substances are more stable. It will go to the reduction direction (forwards).
More negative electrode - right hand substances are more easily oxidised. Left
handed substances are more stable. It will go to the oxidation direction
(backwards).
More negative electrode potential will go in the direction of the oxidation reaction.
Oxidation = Left = More negative
More positive electrode potential will go in the direction of the reduction reaction.
Reduction = Right = Less negative
E cell = E reduced - E oxidised
E cell = E right-hand side- E left-hand side
Standard electrode potential that goes in the direction of the reduction reaction and it has the
more positive electrode potential.
Standard electrode potential that goes in the direction of oxidisation has a more negative
electrode potential.
Predicting the direction of reactions:
1. Find two half equations for the redox reaction.
2. Write them as reduction reaction equations.
3. Use an electrochemical series to work out which half equations have the more negative
electrode potential.
4. Write out the half equations with the more negative electrode potential going in the
backwards reaction (oxidation) and the half equation with the more positive electrode
potential going in the forwards direction (reduction).
5. Combine the two half equations to form a redox equation.
Predict if a reaction will happen:
A list of electrode potentials for different electrochemical half cells.
More positive electrode - left hand substances are more easily reduced. Right
handed substances are more stable. It will go to the reduction direction (forwards).
More negative electrode - right hand substances are more easily oxidised. Left
handed substances are more stable. It will go to the oxidation direction
(backwards).
More negative electrode potential will go in the direction of the oxidation reaction.
Oxidation = Left = More negative
More positive electrode potential will go in the direction of the reduction reaction.
Reduction = Right = Less negative
E cell = E reduced - E oxidised
E cell = E right-hand side- E left-hand side
Standard electrode potential that goes in the direction of the reduction reaction and it has the
more positive electrode potential.
Standard electrode potential that goes in the direction of oxidisation has a more negative
electrode potential.
Predicting the direction of reactions:
1. Find two half equations for the redox reaction.
2. Write them as reduction reaction equations.
3. Use an electrochemical series to work out which half equations have the more negative
electrode potential.
4. Write out the half equations with the more negative electrode potential going in the
backwards reaction (oxidation) and the half equation with the more positive electrode
potential going in the forwards direction (reduction).
5. Combine the two half equations to form a redox equation.
Predict if a reaction will happen:
