Electrode Potential
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Where does an electrical current flow?
From the more reactive metal to the less reactive metal.
When two half cells are joined together, what is formed?
An electrical cell.
What does the potential tell us?
How readily electrons are released by the metal - how good a reducing agent the metal is.
Can electrical potential be measured directly?
No only potential difference can be measured.
What is potential difference also known as?
Voltage
How do you calculate the potential difference?
With a voltmeter.
What completes the electrical circuit?
A salt bridge
What is a salt bridge?
A piece of filter paper soaked in a solution of salt (usually saturated potassium nitrate)
Why is a salt bridge used rather than a wire?
A wire only transfers electrons whereas a salt bridge transfers ions.
What is the standard hydrogen electrode used for?
To compare the tendency of different metals to release electrons.
What happens when a standard hydrogen electrode is used?
Hydrogen gas is bubbled into a solution of H+ ions. Since hydrogen doesn’t conduct, electrical contact is made via a piece of unreactive platinum metal.
What are the standard conditions?
Temperature of 298K A pressure of 100 kPa A concentration of 1 mol/dm^3
What is the potential of the standard hydrogen electrode?
0
What does it mean if the electrode has a negative value? (When using the standard hydrogen electrode)
They are better reducing agents than hydrogen.
Where does oxidation and reduction occur?
Oxidation occurs at the negative electrode. Reduction occurs at the positive electrode.
What does a vertical solid line in a half cell represent?
A phase boundary (different states)
What does a vertical double line in a half cell represent?
A salt bridge
How to calculate EMF?
E(right) - E(left)
How do you know if the reaction is feasible?
The EMF is positive