Electrolysis and Fuel Cells
This list contains resources for teaching about electrolysis and fuels cells at KS4.
The section of the syllabus on electrolysis and fuel cells has considerable overlap with a number of other sections. For example. the extraction of reactive metals, their purification and uses of metals in plating all depend on electrolytic cells. In addition rechargeable batteries (actually cells) can be understood in terms of the reversibility of the reaction involved in generation of power.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance
Links and Resources
This resource allows students to investigate what happens in electrolysis of a simple solution of sodium chloride and is set in the interesting context of electrochemical writing. To understand fully what is happening students need to have covered electrolysis of solutions. They will also need to make the connection between removing hydrogen ions as hydrogen and the pH of the remaining solution (gets higher/more basic). A students worksheet for the activity is included as is a simple method fro making carbon electrodes from a pencil. A useful teacher sheet with background notes is also included.
This resource from the RSC describes the electrolysis of molten lead bromide. The resource includes a detailed method including practical tips and necessary background to enable the process to be carried out safely as a demonstration. Metal crucibles are becoming more popular but it is important in this case to use ceramic ones as suggested to prevent the possible shorting of the circuit due to accidental contact of the carbon rods with the crucible sides. A nice introduction to electrolysis allowing students to see the decomposition of the molten salt to its elements.
This resource describes a micro scale experiment where the migration of ions in an electric field is observed on microscope slides. Assuming the availability of microscopes, this is an interesting way of allowing students to see ions migrating towards the electrodes in an electrolysis cell (or at least seeing the evidence of migration), and illustrates a basic principle of electrolysis (migration of ions to their complementary charged electrode) in an engaging way. Experimental details for teachers and a student worksheet are included.
This resource outlines the electrolysis of a solution of tin (II) chloride resulting in the deposition of tin in crystalline form at the cathode. This is a very visual experiment that most students should find interesting to watch as the tin is deposited. Experimental details for teachers and a student worksheet are included.
This resource describes the electrolysis of a solution of copper sulphate and relates the observations made to both electroplating and to the purification of copper by using active electrodes (electrodes that actually take part in the process). It includes brief teacher notes and a student worksheet giving details of the experiment and including questions to make the above links.
This is an article from the December 2012 issue of Catalyst covering hydrogen fuel cells and their use to power motor vehicles. The article covers the construction and basic principles of hydrogen fuel cells and their use in vehicles as well as giving facts and figures on the advantages of hydrogen powered vehicles over conventional vehicles that rely on petrol or diesel.
This resource from the RSC describes a method for constructing simple cells comprising an electrolyte (sodium chloride solution) and strips of two different metals. The voltage generated by the cell can be related to the separation of the metals in the reactivity series. The further apart they are the higher the voltage recorded. The supporting information is a little thin, for example the student worksheet has a clear diagram of the apparatus but then simply says "try all combinations of metals". Whilst this is fine for some students others may need more explanation and showing how to set up the equipment before they start.
This resource describes two methods for making a hydrogen-oxygen fuel cell.
One approach to teaching about fuel cells is to carry out various demonstrations of how hydrogen reacts with oxygen, how water is electrolysed and how cells (batteries) work.
It may be useful to start with the standard test for hydrogen, or Exploding balloons.
You could make a hydrogen rocket for another spectacular demonstration of the explosive power of these gases. Or take the flaming hands demonstration one step further with this demonstration from the Christmas Lectures.
This resource describes the electrolysis of water with a twist - the evolving gasses are used to create bubbles which will explode!
Then ask the students to use what they have learned from the demos to come up with ideas about how a gas battery (or fuel cell) might work and what reactions would need to take place. As an extension they can apply this to explain applications such as powering cars and the space shuttle.