1.11 - Electrode Potentials Flashcards
What happens when a rod of the metal is dipped into a solution of its own ions
Equilibrium is set up between the solid metal in the aqueous metal ions
What is the simplest salt bridge made of?
Filterpaper soaked in saturated solution of KNO3
Why are salt bridges necessary?
Complete the circuit, but avoid further metal/I am potentials has does not perform electrochemistry.
Allows ion movement to balance the charge do not react with electrodes
What type of species goes on the outside in standard cell notation?
The most reduced species
What happens at the left-hand electrode?
Left-hand electrode is where oxidation occurs.
Left-hand electrode is the half cell with the most negative E value
What happens at the right electrode?
Right-hand electrode is where reduction occurs.
Right-hand electrode is the half cell with the most positive E value
What conditions is the standard hydrogen electrode used in?
Temperature = 298K
Pressure = 100kPa
[H+] = 1.00 moldm^-3
What is the standard hydrogen electrode used for?
Comparing other cells against
Why might you use other standard electrodes occasionally?
They are cheaper/easier/quicker to use and can provide just as good a reference
Platinum is expensive
If an E value is more negative what does it mean in terms of oxidising/reducing power?
Better reducing agent ( easier to oxidise)
What factors will change E values?
Concentration of ions
Temperature
What happens if you reduce the concentration of the ions in the left-hand half cell?
Equilibrium moved to the left to oppose the change of removing ions
This releases more electrons. The E of the left-hand cell becomes more negative so the EMF of the cell increases.
How do you calculate the EMF of a cell from E values?
E cell = E right - E left
When would you use a platinum electrode?
When both the oxidised and reduced forms of the metal are in aqueous solution
Why is platinum chosen?
Inert so does not take part in the electrochemistry, good conductor to complete circuit
