what is the electrolysis of water
Answers
The Electrolysis of Water
Electrolysis apparatus
Water can be decomposed by passing an electric current through it. When this happens, the electrons from the electric current cause an oxidation-reduction reaction. At one electrode, called the cathode, electrons pass into the solution, and cause a reduction. At the other electrode, called the anode, electrons leave the solution completing the circuit, and cause an oxidation.
In order to carry out electrolysis the solution must conduct electric current. Pure water is a very poor conductor. To make the water conduct better we can add an electrolyte to the water. This introduces another problem though. Many electrolytes that we add electrolyze more easily than water. Sulfate ions do not electrolyse as easily as water, so sulfates are often used to enhance the conductivity of the water. At one of the electrodes, electrons (from a current source like a battery) are added to the water molecules (since electrons are added, this is the negative terminal of the battery). The following reduction takes place at the cathode, producing hydrogen gas.
2H2O + 2e- H2(g) + 2OH-
Reduction = Cathode
At the other electrode, electrons are removed from the water (so it is the positive end of the battery) and enter the electrode. This completes the circuit so current can flow. At this electrode, called the anode, water is oxidized:
H2O 1/2O2 (g) + 2H+ + 2e- Oxidation = Anode
Since an oxidation cannot occur without a reduction, these two reactions must occur at the same time. If we add them together, and cancel out the similar terms, we will get the net overall reaction.
2H2O + 2e- H2(g) + 2OH-
H2O 1/2O2 (g) + 2H+ + 2e-
3H2O + 2e- H2 + 1/2O2 (g) + 2H2O + 2e-
which is the same as
H2O H2 + 1/2O2 (g)
Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to the passage of an electric current. The reaction has a standard potential of −1.23 V, meaning it ideally requires a potential difference of 1.23 volts to split water. This technique can be used to make hydrogen gas and breathable oxygen. However, as hydrogen is an important industrial commodity, by far most industrial methods produce hydrogen from natural gas instead, in the steam reforming process
