Electrochemistry Flashcards
Galvanic or voltaic cell
A cell that converts the chemical energy liberated during a redox reaction to electrical energy.
Electrolytic cell
It is a device for using electrical energy to carry out non-spontaneous chemical reactions.
Half-cells or redox couples
The reduction half and the oxidation half of a reaction occur on two different electrodes. A metal electrode dipped in an electrolyte forms a half-cell.
Electrode potential
It is the potential difference developed between the electrode and the electrolyte.
Standard electrode potential
When the concentration of all the species involved in a half-cell is unity then the electrode potential is known as standard electrode potential.
Anode
Cathode
The half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution.
The half-cell in which reduction takes place is called cathode and it has a positive potential with respect to the solution.
Cell potential
It is the difference between the electrode potentials (reduction potentials) of the cathode and anode.
Cell electromotive force (emf)
It is the cell potential of the cell when no current is drawn through the cell.
Electronic conductance
Electrical conductance through metals is called metallic or electronic conductance and is due to the movement of electrons. The electronic conductance depends on
- nature and structure of metal
- number of valence electrons per atom
- temperature (decreases with increase of temp)
Ionic conductance
The conductance of electricity by ions present in the solution is called electrolytic or ionic conductance. It depends on
- nature of electrolyte added
- size of ions produced and their solvation
- nature of the solvent and its viscosity
- concentration of the electrolyte
- temperature (increases with increase of temp)
Conductivity
The conductivity of a solution at any given concentration is the conductance of one unit volume of solution kept between the platinum electrodes with unit area of cross section and at a distance of unit length.
Molar conductivity
Molar conductivity of a solution at a given concentration is the molar conductance of the volume V of solution containing one mole of electrolyte kept between two electrodes with area of cross section A and distance of unit length.
Limiting molar conductivity
When concentration approaches zero, the molar conductivity is known as limiting molar conductivity.
Kohlrausch law of independent migration of ions
The law states that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte.
Faraday’s first law of electrolysis
The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.
