Electrode potentials Flashcards
What are electrochemical cells made out of?
Two different metals are dipped in a solution that contains their ions and are connected by a wire.
When your solution contains two aqueous ions what type of electrode must you have?
platinum
Why is a platinum electrode used?
- To provide a reaction surface.
- It is inert and won’t react with the ions.
- It conducts electricity.
What is the role of a salt bridge?
It allows ions to move and carry charge.
What is an electrode potential?
How easily a metal is oxidised.
When drawing electrochemical cells which species do you put towards the middle?
The most oxidised species.
How do you calculate the Emf of a cell?
E of the right hand - E of the left hand
Why must the cell potential be measured under standard conditions?
Changing the conditions changes the position of the equilibrium and that changes the cell potential.
What are the standard conditions in a SHE?
- 1 mol dm -3
- 100 kPa
- 298K
Where would you find the strongest reducing agent in an electrochemical series?
The most negative end of the right-hand side.
Where would you find the strongest oxidising agent in an electrochemical series?
The most positive end of the left-hand side.
How do you recharge a rechargeable battery?
A current is supplied which forces the electrons to flow in the opposite direction and reverse the reaction.
What are the half equations for a hydrogen fuel cell in alkaline conditions?
negative electrode: H2+ 2OH– = 2H2O + 2e–
positive electrode: O2 + 2H2O+ 4e– = 4OH
What are the advantages of using fuel cells?
- There are no toxic waste chemicals to dispose of.
- They don’t need to be recharged as oxygen and hydrogen are supplied.
What are the disadvantages of using fuel cells?
- Making the hydrogen is expensive and storing it is dangerous as it is flammable.
