In salt water, sodium chloride is completely ionized and water molecules are weakly ionized, so there are four ions: Na+, H+, Cl- and OH-.
NaCl=Na++Cl-
H2O =H++OH-
When DC power is connected, the negatively charged OH- and Cl - Moving towards the anode, the positively charged Na+ and H+ move towards the cathode.
Under such electrolysis conditions, at the anode, Cl- loses electrons more easily than OH- and is oxidized to chlorine atoms. Chlorine atoms combine into chlorine molecules to release chlorine gas.
2Cl--2e=Cl2↑(oxidation reaction)
At the cathode, H+ can obtain electrons more easily than Na+, so H+ continually obtains electrons from the cathode and is reduced to hydrogen atoms Hydrogen atoms The two combine to form hydrogen molecules and release hydrogen gas from the cathode.
2H++2e=H2↑ (reduction reaction)
As H+ continually obtains electrons on the cathode, hydrogen gas is generated and released, destroying the ionization balance of nearby water, and water molecules continue to expand. ionize to H+ and OH-, and H+ continues to gain electrons. As a result, the number of OH- in the solution increases relatively. A soda solution is thus formed near the cathode. The general chemical equation for the electrolysis of saturated salt water can be expressed as follows:
2NaCl+2H2O===Electrolysis====2NaOH+H2↑+Cl2↑
Salt and water do not react because salt and water do not form new substances when mixed.
We can only say that the salt and water have undergone chemical changes and the salt has dissolved in the water.
Sodium chloride (sodium chloride), colorless cubic crystals or white crystals, is the main component of table salt. Easily soluble in water ande glycerol, slightly soluble in ethanol and liquid ammonia, insoluble in hydrochloric acid and slightly deliquescent in air.
It is mainly used for manufacturing industrial raw materials such as chlorine, hydrogen, bleaching powder and metallic sodium, as well as for salting out soap, tanning leather, seasoning food and marinating fish, meat and vegetables. If you take too much, you can easily get high blood pressure.