Electrode potentials Flashcards
What is the salt bridge made out of?
Filter paper SOAKED in KNO3
(aq)
- The salt bridge allows ions to flow through and balance out the charge
What is an electrochemical cell?
Two different metals dipped in a solution of their own ions, connected by a wire ( external circuit)
Electrochemical cells make electricity (practical)
zinc/copper
what happens?
1) Zinc loses electrons easier than copper, so zinc is oxidised to form Zn2+ (aq) ions . This releases electrons into the wire. LEFT SIDE = OXIDATION
2) In the other half cell, the same number of electrons are taken from the wire, reducing Cu2= ions into to copper atoms. RIGHT SIDE = REDUCTION
what does EMF stand for
Electromotive force
why are some electrodes made out of platinum
It is an inert metal so won’t react with the ions
Reactions that occur at electrochemical cells are…
reversible half equations
mostly reduction ( so electrons on the left side)
Does a metal that is easily oxidised ( easily loses electrons) have a positive or negative electrode potential?
Very negative electrode potential
the lower the electrode potential the easier it is to be oxidised
Measuring electrode potential of a half cell against standard hydrogen electrode (practical):
(ONE THING TO REMEMBER)
- as cell potential is affected by (temp, pressure, conc)
- standard conditions are used.
Standard electrode potential of a cell def:
Standard electrode potential of a cell, is the voltage measured under standard conditions when the half cell is connected to a standard hydrogen electrode.
What are the standard conditions;
298K
100kpa
1moldm-3 ( any solution must have this concentration)