Accumulators
To set up a simple accumulator and demonstrate the possibility of storing energy as chemical energy.
What students learn
The science behind this experiment
There is a class of galvanic cells in which the electrolysis can be reversed. These cells can be charged by an electric current and then later produce a current by reversing the electrode reactions. During charging the energy is stored as chemical energy, and the cells are sometimes called accumulators.
Equipment used
- Connecting wires, red — 2522.03-04
- Connecting wires, black — 2522.04-08
- Crocodile clips — 2531.52
- Lead electrodes — 4716.24
- Test cell covers — 4718.10
- Beaker 50 ml — 1118.15
- Lamp holder — 4762.36
Chemicals and reagents
- Sulphuric acid 0.5 M — R:35 S:26-30-45
Safety notes
- Lead compounds produced during the process are poisonous and harmful to the environment. Always wear protective goggles and gloves.
Questions for students
- What voltage did you measure on the starting cell?
- What happens during the charge process?
- What voltage did you measure after the charge process?
What to expect
<p>A 0 Volt difference of potential is measured since the half cells are the same, both metals and concentration of the solution.</p><p>A current is produced in the circuit and electrolysis produces bubbles at the electrodes because of the electrolysis that occurs producing oxygen and hydrogen.</p><p>During this time electrodes accumulate an electric charge. REACTIONS.</p><p>By passing an electric current through the cell, electrolysis occurs Pb SO4 + 2e – → Pb + SO42– Cathode (+).</p><p>Pb SO4 + 2 H2O → PbO2 + 4H+ + SO42 + 2 e– Anode (–).</p><p>There is also some production of oxygen (cathode) and hydrogen (anode),because of the electrolysis of water.</p><p>Because the lead dioxide has a brown colour and the lead is grey, the electrodes look different and a new cell with different electrodes has been created.</p><p>The difference of potential between the electrodes is approximately 2 V. When the current supply is suspended, electrolysis ceases.</p><p>The charges accumulated on the electrodes are discharged because the reaction can be inverted.</p><p>When the energy in the cell is used, the reactions reverse as follows.</p><p>PbO2 + H2SO4 + 2 e– → Pb SO4 + H2O Cathode (+).</p><p>Pb + SO42– → Pb SO4 + 2 e–Anode (–).</p><p>So during these processes the oxidation state of lead changes.</p><p>The lamp lights up and a current reading is displayed.</p><p>The current slowly decreases until the bulb goes out. The accumulator is now discharged but it is possible to recharge it again.</p>
Disposal
Dispose of the liquids into the waste container.
Run this experiment in your classroom
This experiment is part of the ATP Mobile Lab — a self-contained laboratory that turns an ordinary classroom into a working science lab, with over 200 experiments in physics, chemistry, biology, robotics and engineering. Gali, the AI tutor built into ATP Connect, guides students through each step and answers their questions at the bench.
See the Mobile LabTalk to our team