1.11 Electrode potentials and electrochemical cells (Redox A2)
Lessons 17.11.2014, 18.11.2014, 24.11.2014, 25.11.2014 (click here for pdf download)
Redox reactions take place in electrochemical cells where electrons are transferred from the reducing agent to the oxidising agent indirectly via an external circuit.
A potential difference is created that can drive an electric current to do work.
Electrochemical cells have very important commercial applications as a portable supply of electricity to power electronic devices such as mobile phones, tablets and laptops. On a larger scale, they can provide energy to power a vehicle.
Required practical 8
Measuring the EMF of an electrochemical cell.
Commercial applications of electrochemical cells - Electrochemical cells can be used as a commercial source of electrical energy. Cells can be non-rechargeable (irreversible), rechargeable or fuel cells. The simplified electrode reactions in a lithium cell: Positive electrode: Li+ + CoO2 + e– → Li+[CoO2]– Negative electrode: Li → Li+ + e– Students should be able to: • use given electrode data to deduce the reactions occurring in non-rechargeable and rechargeable cells and Electrode potentials and cells - IUPAC convention for writing half-equations for electrode reactions. The conventional representation of cells. Cells are used to measure electrode potentials by reference to the standard hydrogen electrode. The importance of the conditions when measuring the electrode potential, E (Nernst equation not required). Standard electrode potential, EƟ, refers to conditions of 298 K, 100 kPa and 1.00 mol dm-3 solution of ions. Standard electrode potentials