What is produced at the negative pole during electrolysis?

• A. Sodium chloride
• B. Sodium hydroxide
• C. Hydrochloric acid
• D. Potassium hydroxide

Answer: (B)

During electrolysis, the negative pole, known as the cathode, is where reduction reactions occur. In the context of the question, when a sodium chloride solution undergoes electrolysis, the ions present play a crucial role in determining what is produced at the cathode.

At the negative pole, water molecules are often reduced to produce hydroxide ions. This reaction can be represented by the equation:

2 H₂O + 2 e⁻ → H₂ + 2 OH⁻.

The generation of hydroxide ions (OH⁻) is directly related to the formation of sodium hydroxide (NaOH), which occurs as sodium ions (Na⁺) from the dissolved sodium chloride combine with the hydroxide ions produced at the cathode. Therefore, the result at the negative electrode during the electrolysis of sodium chloride solution is indeed sodium hydroxide.

The other substances listed are products of different reactions or processes. Sodium chloride on its own would not yield hydrochloric acid at the cathode, nor would potassium hydroxide be produced unless potassium chloride were present instead. Additionally, while sodium hydroxide is produced at the cathode, sodium chloride is primarily present in the electrolyte and does not undergo transformation into a product at the negative pole. Thus