Water electrolysis with acids
To carry out the electrolysis of water in an acidic environment.
Lo que aprenden los alumnos
La base científica de este experimento
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.
Equipo utilizado
- 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
Productos químicos y reactivos
- Sulphuric acid solution 0.1 M — R:35 S:26-30-45
Notas de seguridad
- Hydrogen and air mixtures are explosive. Ensure that there are no naked flames near the apparatus.
Preguntas para los alumnos
- 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?
Qué puedes esperar
<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>
Eliminación
Dispose of the solution into the waste container.
Realiza este experimento en tu clase
Este experimento forma parte del « Mobile Lab » de ATP, un laboratorio autónomo que convierte un aula normal en un laboratorio de ciencias en pleno funcionamiento, con más de 200 experimentos de física, química, biología, robótica e ingeniería. « Gali », el tutor de IA integrado en ATP Connect, guía a los alumnos paso a paso y responde a sus preguntas en la mesa de trabajo.
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