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Water electrolysis with acids
Chimica

Water electrolysis with acids

To carry out the electrolysis of water in an acidic environment.

Elettrochimica
electrolysis of water; acids; gas collection

Cosa imparano gli studenti

La scienza alla base di questo esperimento

Electrolysis is a process which produces chemical changes due to the flow of a direct electric current through an electrolyte. When a current flows through a conducting solution, the ionic species undergo redox reactions.

2 H2O ↔ H3O + + OH –.

Adding sulphuric acid increases the conductivity by generating electrolyte as follows.

Direct Electric current causes the following reactions in the acidified water at the platinum electrodes.

At the cathode (–) 4H3O + + 4 e – → 2 H2 + 4H2O At the anode (+) 6 H2O → O2 + 4H3O + + 4 e –.

( O2 / H2O )( O2 / H2O )At the anode water molecules are oxidised because their electrode potential ( E0.

( H( HAt the cathode H3O+ ions are reduced because their potential ( E0 + / H2 ) = + 0.00 v ) is greater.

( H2O / H2 )( H2O / H2 )than that of water molecules H2O ( E0.

Attrezzatura utilizzata

  • U tube with side outlets — 1276.10
  • Platinum electrodes — 4716.12
  • Connecting wires, red — 2522.03-04
  • Connecting wires, black — 2522.04-08
  • DC power supply

Sostanze chimiche e reagenti

  • Sulphuric acid solution 0.1 M — R:35 S:26-30-45

Note sulla sicurezza

  • Hydrogen and air mixtures are explosive. Ensure that there are no naked flames near the apparatus.

Domande per gli studenti

  • Describe what happens in the apparatus.
  • What happens on igniting the test tubes? State where hydrogen and oxygen are produced.
  • Why do we use a dilute acidic solution instead of distilled water?

Cosa aspettarsi

<p>Passage of the electric current causes bubbling at the electrodes.</p><p>The gas collected at the cathode () pops, indicating the presence of hydrogen.</p><p>The gas collected at the anode (+) brightens up the flame indicating the presence of oxygen.</p><p>At the cathode () H+ are reduced to hydrogen.</p><p>At the anode (+) water molecules are oxidized to oxygen and H+ ions.</p><p>Distilled water does not conduct electricity but the presence of some electrolyte allows an electrical current to flow as demonstrated in the previous experiments.</p>

Smaltimento

Dispose of the solution into the waste container.

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Questo esperimento fa parte dell’ATP “ Mobile Lab ” — un laboratorio autonomo che trasforma una normale aula in un vero e proprio laboratorio scientifico, con oltre 200 esperimenti di fisica, chimica, biologia, robotica e ingegneria. “ Gali ”, il tutor basato sull’intelligenza artificiale integrato in ATP Connect, guida gli studenti in ogni fase e risponde alle loro domande direttamente al banco di lavoro.

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