Question

Brine solution on electrolysis will not give: (a) \(\mathrm{H}_{2}\) (b) \(\mathrm{O}_{2}\) (c) \(\mathrm{NaOH}\) (d) \(\mathrm{Cl}_{2}\)

Short answer

The correct option is (b) \( \mathrm{O}_{2} \).

Step-by-step solution

Understanding Electrolysis of Brine

Brine is a concentrated solution of sodium chloride (NaCl). When brine undergoes electrolysis, it breaks down into its constituent elements and other products.

Analyzing The Products

Electrolysis of brine results in the formation of hydrogen gas (H₂) at the cathode, chlorine gas (Cl₂) at the anode, and sodium hydroxide (NaOH) in the solution.

Identifying the Missing Product

The products collected from the experiment do not include oxygen gas (O₂). Therefore, during the electrolysis of brine, oxygen gas is not formed as a product.

Key concepts

Sodium Chloride (NaCl)

Sodium chloride, commonly known as table salt, is a critical component in the electrolysis of brine. Brine is essentially a highly concentrated solution of NaCl mixed with water.

During electrolysis, electricity is passed through the brine to cause a chemical transformation. NaCl gets split into its elements, which form important industrial chemicals. This process of breaking down NaCl is the starting point for creating other useful products.

• NaCl in brine undergoes a process called dissociation, where sodium ( ext{Na}^+) and chloride ( ext{Cl}^-) ions separate.
• The electrical current helps these ions move toward the electrodes, where they participate in chemical reactions.

Understanding NaCl's role in electrolysis helps in grasping how this simple compound can produce essential materials.

Hydrogen Gas (H₂)

Hydrogen gas is one of the valuable products obtained when brine is electrolyzed. It is formed at the cathode, which is the negatively charged electrode. As the electrolysis process occurs:

- Positively charged hydrogen ions ( ext{H}^+) present in the solution gain electrons at the cathode. - This collection of electrons transforms the ions into hydrogen gas ( ext{H}_2), which bubbles up and can be collected.
Hydrogen is highly versatile and finds applications in numerous fields. It is a clean energy source and plays a role in various chemical manufacturing processes.

Sodium Hydroxide (NaOH)

Sodium hydroxide, commonly known as lye or caustic soda, is another product formed during the electrolysis of brine. It is generated in the solution and can be extracted for further use.

Here's how it happens:

• When sodium ions ( ext{Na}^+) combine with hydroxide ions ( ext{OH}^-), they form ext{NaOH}.
• Hydroxide ions are produced from the disassociation of water molecules at the cathode.

NaOH is extensively used in various industries. It is crucial in paper manufacturing, soap production, and as a strong cleaning agent. This compound's formation during electrolysis demonstrates how a simple process can yield such a powerful and important material.

Chlorine Gas (Cl₂)

Chlorine gas is generated at the anode during the electrolysis of brine. The anode is the positively charged electrode, where negative ions are attracted.

During electrolysis:

• Chloride ions ( ext{Cl}^-) migrate to the anode.
• These ions relinquish their extra electrons, which causes them to form chlorine gas ( ext{Cl}_2).

Chlorine gas has numerous applications, including disinfecting water in swimming pools and in bleach production. It also plays a key role in producing polyvinyl chloride (PVC) and other chemicals. Understanding its formation during electrolysis helps highlight the process's efficiency in creating vital products from straightforward chemical reactions.