Na+H2O ---------NaOH+H2+ heat
This process is know as chlor-alkali process and it is done by the electrolysis of aqueous solution of NaCl .. hope it helps:)

**Chemical Equation Involved in the Preparation of Sodium Hydroxide**

The process involved in the preparation of sodium hydroxide (NaOH) is known as the chlor-alkali process. It is an industrial method used to produce sodium hydroxide, chlorine gas, and hydrogen gas. The primary chemical reaction occurring during this process is electrolysis, which takes place in an electrolytic cell.

**Electrolysis of Sodium Chloride Solution:**

The electrolysis of sodium chloride (NaCl) solution is the fundamental step in the preparation of sodium hydroxide. The process involves the following chemical reactions:

1. **Cathode Reaction:** At the cathode (negative electrode), water molecules (H2O) are reduced, leading to the formation of hydrogen gas (H2) and hydroxide ions (OH-):

2H2O + 2e- → H2 + 2OH-

2. **Anode Reaction:** At the anode (positive electrode), chloride ions (Cl-) are oxidized, resulting in the formation of chlorine gas (Cl2) and water:

2Cl- → Cl2 + 2e-

**Overall Reaction:**

The overall reaction for the electrolysis of sodium chloride solution can be represented as:

2NaCl + 2H2O → Cl2 + H2 + 2NaOH

This reaction shows that for every two moles of sodium chloride (NaCl) and two moles of water (H2O), one mole of chlorine gas (Cl2), one mole of hydrogen gas (H2), and two moles of sodium hydroxide (NaOH) are produced.

**Explanation of the Process:**

1. **Electrolytic Cell:** The electrolysis of sodium chloride solution is carried out in an electrolytic cell. The cell consists of two electrodes (cathode and anode) immersed in a solution of sodium chloride (NaCl) known as brine.

2. **Cathode:** The cathode is connected to the negative terminal of a direct current (DC) power source. Here, water molecules (H2O) are reduced to hydrogen gas (H2) and hydroxide ions (OH-) due to the supply of electrons.

3. **Anode:** The anode is connected to the positive terminal of the power source. Chloride ions (Cl-) present in the brine solution are oxidized to chlorine gas (Cl2) at the anode.

4. **Separation:** The chlorine gas (Cl2) and hydrogen gas (H2) produced during electrolysis are collected separately. The sodium hydroxide (NaOH) formed in the solution remains dissolved.

5. **Product Recovery:** The sodium hydroxide solution is then concentrated, purified, and further processed to obtain solid sodium hydroxide in the form of pellets, flakes, or granules.

Overall, the chlor-alkali process is an important method for the large-scale production of sodium hydroxide. It utilizes the electrolysis of sodium chloride solution to generate sodium hydroxide, chlorine gas, and hydrogen gas. This process has significant industrial applications in various sectors such as chemical manufacturing, water treatment, soap production, and more.