Electrochemical cells

Nature of science:

Ethical implications of research—the desire to produce energy can be driven by social needs or profit. (4.5)

• Voltaic cells convert energy from spontaneous, exothermic chemical processes to electrical energy.
• Oxidation occurs at the anode (negative electrode) and reduction occurs at the cathode (positive electrode) in a voltaic cell.

Electrolytic cells:

• Electrolytic cells convert electrical energy to chemical energy, by bringing about non-spontaneous processes.
• xidation occurs at the anode (positive electrode) and reduction occurs at the cathode (negative electrode) in an electrolytic cell.

Applications and skills:

• Construction and annotation of both types of electrochemical cells.
• Explanation of how a redox reaction is used to produce electricity in a voltaic cell and how current is conducted in an electrolytic cell.
• Distinction between electron and ion flow in both electrochemical cells.
• Performance of laboratory experiments involving a typical voltaic cell using two metal/metal-ion half-cells.
• Deduction of the products of the electrolysis of a molten salt.

• Research in space exploration often centres on energy factors. The basic hydrogen–oxygen fuel cell can be used as an energy source in spacecraft, such as those first engineered by NASA in the USA. The International Space Station is a good example of a multinational project involving the international scientific community.

Theory of knowledge:

• Is energy just an abstract concept used to justify why certain types of changes are always associated with each other? Are concepts such as energy real?

Utilization:

• Fuel cells.
• Heart pacemakers.

Syllabus and cross-curricular links:
Option C.6—fuel cells
Physics topic 5.3—electrochemical cells Aims:

• Aim 6: Construction of a typical voltaic cell using two metal/metal-ion half-cells.
• Aim 6: Electrolysis experiments could include that of a molten salt. A video could also be used to show some of these electrolytic processes.
• Aim 8: Although the hydrogen fuel cell is considered an environmentally friendly, efficient alternative to the internal combustion engine, storage of hydrogen fuel is a major problem. The use of liquid methanol, which can be produced from plants as a carbon neutral fuel (one which does not contribute to the greenhouse effect), in fuel cells has enormous potential. What are the current barriers to the development of fuel cells?

• For voltaic cells, a cell diagram convention should be covered.