Electrochemistry: Galvanics and Electrolytics Flashcards
Redox reaction
a reaction involving a transfer of electrons.
Oxidation
the loss of electrons (OILe-)
Reduction
the gain of electrons (RIGe-)
Oxidising agent
a substance that accepts electrons (it is reduced in a redox reaction)
Reducing agent
a substance that donates electrons (it is oxidised in a redox reaction)
A Galvanic cell
converts chemical energy to electrical energy by means of self - sustaining electrode reactions.
A standard galvanic cell consists of:
two elemental electrodes (often metals but not always)
each element immersed in a solution containing ions of that element.
the two solutions are placed in separate containers that prevents them from rapidly mixing – these form the ½ cells.
a salt bridge solution made from a group 1 metal nitrate solution.
Standard conditions for Galvanic cells:
Temperature of 25°C (298K)
Solution concentrations of 1 M
Gas pressures of 1 atm
What affects the current generated by a Galvanic cell?
Surface area of electrodes makes the most dramatic effect
Temperature and concentration of electrolytes affect rates too but to a lesser degree .
Decreasing the internal resistance of the cell (see salt bridge) will also increase the current delivered.
The cell can deliver current up until the reaction has reached equilibrium or gone to completion.
The function of the salt bridge can be stated:
- Completes the circuit.
- Maintains electrical neutrality of the two ½ cell solutions.
Substances to use an electrode
Platinum
carbon
Electrolyte
A substance that can conduct electricity by forming free ions when molten or dissolved in a solution
A liquid that conducts electricity due to the presence of free ions.
Electrolysis
Electrode reactions that are sustained by a supply of electrical energy. There is conversion of electrical energy into chemical energy.
Electrode
A solid electrical conductor through which electrical current enters or leaves an electrolytic or galvanic cell.
