In the chlor-alkali process, sodium chloride (NaCl) is electrolyzed to produce chlorine gas (Cl₂), hydrogen gas (H₂), and sodium hydroxide (NaOH). The original sodium and chlorine ions in the starting material, NaCl, are transformed into different chemical compounds as a result of the electrolysis process. Here's what happens to the original sodium and chlorine:

Sodium (Na): The sodium ions (Na+) in NaCl are reduced at the cathode (negative electrode) during electrolysis. Reduction involves gaining electrons, so each Na+ ion gains one electron to become a neutral sodium atom (Na). These sodium atoms then react with water (H₂O) present in the electrolytic solution to form sodium hydroxide (NaOH) and hydrogen gas (H₂). The overall reaction for this process is:

2Na+ + 2H₂O + 2e- → 2NaOH + H₂

Chlorine (Cl): The chloride ions (Cl-) in NaCl are oxidized at the anode (positive electrode) during electrolysis. Oxidation involves losing electrons, so each Cl- ion loses one electron to become a neutral chlorine atom (Cl). These chlorine atoms then react with each other to form chlorine gas (Cl₂), which is released as a product of the electrolysis. The overall reaction for this process is:

2Cl- → Cl₂ + 2e-

Therefore, the original sodium ions from NaCl are converted into sodium atoms, which react with water to form sodium hydroxide. The original chloride ions from NaCl are converted into neutral chlorine atoms, which combine to form chlorine gas. These products, sodium hydroxide and chlorine gas, are the valuable end products of the chlor-alkali process and are widely used in various industries.