Shaillee Kaushal is teaching live on Unacademy Plus
Electrochemistry - l XII - 03
Introduction: Electrochemistry deals with electrical and chemical energies. It is broadly divided into two categories namely () production of chemical charge by electrical energy (phenomenon of electrolysis) and (i) conversion of chemical energy into electrical energy i.e generation of electricity by spontaneous redox reactions. .Substances which allow the passage of electric current through them are called electrical conductors. Those which do not allow the flow of electric current through them are called insulators.
Types of Conductors - Metallic or electronic Electrolytic conductors conductors
Distinction between metallic and electrolvtic conduction Metallic conduction Electrolytic conduction 1. Electric current flows by movement ofElectric current flows by movement electrons. 2. No chemical change occurs 3. It does not involve the transfer ofany matter 4. Resistance increases with increase in temperature ofions Ions are oxidized or reduced at the elctrodes It involves the transfer ofmatter in the form ofions. Resistance decreases with increase oftemperature.
Electrolysis: The process of chemical decomposition of an electrolyte by passage of electric current through its solution is called electrolysis For eg. Cathode: Anode Cl eCl CI +Cl Cl2 H+H H2 The device in which electrolysis is carried out by using electricity or in which conversionofelectrical energy into chemical change is done is known as an electrolytic cell An electrolytic cell consists of a vessel for the electrolytic solution or fused electrolyte and two metallic electrodes inversed in the vessel which are connected to a source of electric current. The metallic electrodes which do not react with ions or final products are called inert electrodes
Preferential discharge theory: If an electrolytic solution consists of more than two ions and electrolysis is done, it is observed that all the ions are not discharged at the electrodes simultaneously but certain ions are liberated at the electrodes in preference to others. This is explained by preferential discharge theory It states that more than one type of ions are attracted towards a particular electrode, then the one discharged is the ion which requires least energy The potential at which the ion is discharged or deposited on the appropriate electrode is termed the discharge or deposition potential. The values for discharge potential are different for different ions