9.5 Standard Electrode Potential Flashcards
What is the standard electrode potential?
The EMF of a half cell connected to a standard hydrogen electrode measured under standard condition (solution of concentration 1moldm-3 pressure of 100 kPa and temperature of 298k).
What is the half equation for the standard hydrogen electrode?
H+ (aq) + e- —–> 1/2H2 (g) 0.00V
How is the standard electrode potential of a half cell measured?
By connecting it to the standard hydrogen electrode.
How are standard electrode potential written?
Always written as a reduction and show the favourability of a particular reduction reaction related to the standard hydrogen electrode.
What does it show if the voltage for the cell is negative?
It is unfavourable relative to the standard hydrogen electrode.
When is the cell potential?
The voltage of a cell formed hen the two half cells are connected.
What is the method for working out a cell potential?
Write down the half equation and standard electrode potentials for the two reactions.
Change the sign of the more negative and add it to the other standard electrode potential.
What does a positive value show?
A spontaneous reaction.
What does a very positive value for standard electrode potential mean?
The reduction reaction is very favourable relative to the standard hydrogen electrode and the substance has a very strong tendency to pick up electrons from other species ie. it is a strong oxidising agent.
What does a very negative value for standard electrode potential mean?
Indicates a strong reducing agent.
In the IB data booklet table what do species further up the table mean?
They are stronger reducing agents, the reduced species is the reducing agent on the right and will reduce species flow them.
In the IB data booklet table what do species further down the table mean?
They are stronger oxidising agents, the coded species is the oxidising agent on the left and will oxidise species above them.
What will a species with a more positive electrode potential do to a species with a less positive electrode potential?
A species with a more positive electrode potential will oxidise a substance with a less positive electrode potential.
How is the standard electrode potential and the Gibbs free energy changed related?
delta G = -nFE
where n is the number of electrons transferred in a particular redox reaction and F is the Faraday constant.
