Electrode potentials and electrochemical cells Flashcards
What are the IUPAC rules for cell diagrams?
The positive electrode (reduction) should be on the right side except when doing a standard electrode potential when hydrogen is always drawn on the left
What are cells used for
Measure electrode potential in reference to the standard electrode potential (hydrogen)
What are the conditions for the standard electrode potential
298 K
100 KPa
1.00 mol dm3 of ions
What happens to the more positive electrode potential
It is reduced
What happens to the more negative electrode potential
It is oxidised
Should equations be written in the reduction or oxidation direction
Reduction
What can electrochemical cells be used for
A source of energy
What are the simplified electrode reactions in a lithium cell
Positive electrode = Li+ + CoO2 + e- —> Li+[CoO2]-
Negative electrode = Li —> Li + + e-
What are the 3 types of cells
Non-rechargeable (irreversible)
Rechargeable (Reversible)
Fuel cells
What are fuel cells used for
Generate an electric current and don’t need to be electrically recharged
What are the equations of a hydrogen oxygen fuel cell in alkaline conditions
2H2O + 2e- —> H2 + 2OH-
O2 + 2H2O + 4e- —> 4OH-
What are some advantages of hydrogen fuel cell
Cleaner as just produce water vapour
More efficient than petrol as it often incompletely combusts
No need to transport expensive petrol
Renewable resource
What are some weakness’s of hydrogen fuel cells
Very flammable
Pure H2 isn’t naturally abundant. we must spilt water requiring a lot of energy
They are very big
What is the meaning of an electrochemical series
List of electrode potentials in order
What is the salt bridge made of
KNO3
