Innovating Science™ AP Chemistry Kits:Electrochemical Cells

Description

• The tendency of oxidation-reduction reactions is to proceed to an equilibrium state
• In electrochemical cells, these reactions provide another way for us to express the driving force in chemical reactions
• When reagents that accept or donate electrons are arranged so that the electrons can enter or leave the reaction through a metallic conductor, an electrochemical cell is established
• A half-cell contains a metal in contact with a solution of its salt
• Each metal will develop a different electrical potential based on its electron configuration
• The standard reduction potential listed in various references is the voltage that a half-cell develops when combined with a hydrogen half-cell
• First, construct a simple chemical battery and determine from the standard reduction potentials what the output of the battery will be (if a voltmeter is available the actual and theoretical voltages can be compared)
• Second, construct an electrolysis cell and demonstrate how hydrogen and oxygen can be produced from the electrolysis of water
• Electrolysis cell is the reverse of a battery where a voltage higher than the reversible electromotive force of the cell is applied to the electrodes In a cell containing water and an electrolyte, the oxidation reaction occurring at the anode produces oxygen gas while the reduction occurring at the cathode produces hydrogen gas By the addition of a pH indicator, the oxidation-reduction reactions can be monitored visually Gases produced are collected in inverted test tubes and the volumes of hydrogen and oxygen are compared