Accumulators
To set up a simple accumulator and demonstrate the possibility of storing energy as chemical energy.
Cosa imparano gli studenti
La scienza alla base di questo esperimento
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.
Attrezzatura utilizzata
- 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
Sostanze chimiche e reagenti
- Sulphuric acid 0.5 M — R:35 S:26-30-45
Note sulla sicurezza
- Lead compounds produced during the process are poisonous and harmful to the environment. Always wear protective goggles and gloves.
Domande per gli studenti
- What voltage did you measure on the starting cell?
- What happens during the charge process?
- What voltage did you measure after the charge process?
Cosa aspettarsi
<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>
Smaltimento
Dispose of the liquids into the waste container.
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