Electrolysis of Aqueous Compounds

Electrolysis of Concentrated Hydrochloric Acid 

In the electrolysis of Concentrated Hydrochloric Acid (HCl), 

• Hydrogen gas (H2) is produced at the cathode 
• Chlorine gas (Cl2) is produced at the anode.

At the Anode (Positive Electrode):

The anode attracts negatively charged ions (anions) from the concentrated Hydrochloric Acid.

• At the anode, Chloride  ions (Cl–) are oxidized.
• Each chloride ion loses one electron and forms chlorine gas (Cl2):

                      2 Cl– → Cl2 + 2 e–

Cathode (Negative Electrode):

The cathode attracts positively charged ions (cations) from the concentrated Hydrochloric Acid.

• At the cathode, hydrogen ions (H⁺) are reduced.
• Each hydrogen ion gain electrons and forms Hydrogen gas:

2 H⁺ + 2 e– → H2

The overall reaction of the electrolysis of concentrated hydrochloric acid can be represented as follows: 

2 HCl → Cl2 + H2

Observations:

• At the anode: 
  • Chlorine Gas Liberation: As the electric current is passed through the concentrated hydrochloric acid, you will observe the evolution of pale greenish-yellow chlorine gas (Cl2) at the anode.
• At the cathode: 
  • Hydrogen Gas Liberation: you will observe the evolution of colorless, odorless hydrogen gas (H2).

Electrolysis of concentrated hydrochloric acid is essential for the production of chlorine gas, which is used in various industrial applications, including the manufacture of chemicals like PVC (polyvinyl chloride).

Chlorine gas produced through this process finds use in water treatment, disinfection, and as a chemical intermediate in the production of various compounds.

Safety precautions include wearing appropriate protective gear, working in a well-ventilated area, and handling concentrated hydrochloric acid with care due to its corrosive nature.

Hazards include the potential release of toxic chlorine gas and the corrosive properties of hydrochloric acid. Adequate ventilation and safety equipment are essential.

Electrolysis of Sodium Chloride (NaCl)

In the electrolysis of Sodium Chloride (NaCl), 

• Sodium Metal (Na) is produced at the cathode 
• Chlorine gas (Cl2) is produced at the anode.

At the Anode (Positive Electrode):

The anode attracts negatively charged ions (anions) from the concentrated Hydrochloric Acid.

• At the anode, Chloride  ions (Cl–) are oxidized.
• Each chloride ion loses one electron and forms chlorine gas (Cl2):

                      2 Cl– → Cl2 + 2 e–

Cathode (Negative Electrode):

The cathode attracts positively charged ions (cations) from the aqueous Sodium Chloride.

• At the cathode, sodium ions (Na⁺) are reduced.
• Each sodium ion gain electrons and forms Sodium Metal:

2 Na+ (aq) + 2e– → 2Na (l)

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

2 NaCl (aq) → 2Na (l) + Cl2 (g)

Observations:

• At the anode:

Chlorine gas (Cl2) is produced. It has a distinct yellow-green color and a characteristic smell.

• At the cathode:

Sodium metal (Na) is formed as a molten substance. However, in an aqueous solution, sodium hydroxide (NaOH) may also be produced due to the presence of water.

The electrolysis of sodium chloride is used in the production of chlorine gas and sodium metal.

Chlorine gas has various industrial applications, including the production of PVC, water disinfection, and bleach.

Sodium metal is highly reactive and is not typically obtained in pure form through electrolysis of aqueous sodium chloride due to the presence of water. It is often obtained through other methods.

Electrolysis of Dilute Sulfuric Acid – H2SO4

In the electrolysis of Dilute Sulfuric Acid (H2SO4), 

• Sodium Metal (Na) is produced at the cathode 
• Chlorine gas (Cl2) is produced at the anode.

At the Anode (Positive Electrode):

The anode attracts negatively charged ions (anions) from the Dilute Sulfuric Acid:

• The sulfuric acid (H2SO4 ) loses oxygen atoms and forms sulfate ions (SO4-2) while releasing oxygen gas: 

2 H2SO4 → 2 H2O + O2 + 2 SO4-2

Cathode (Negative Electrode):

The cathode attracts positively charged ions (cations) from the aqueous Sodium Chloride.

• At the cathode, hydrogen ions (H+) from the sulfuric acid gain electrons and form hydrogen gas: 

2 H+ + 2 e– → H2

The overall reaction of the electrolysis of Dilute Sulfuric Acid can be represented as follows: 

2 H2SO4 → 2 H2 + O2 + 2 SO4-2

Observations:

• At the anode:

Oxygen gas (O2) is produced. It is colorless with no distinct smell. 

• At the cathode:

Evolution of bubbles will be observed. These bubbles are hydrogen gas (H2).

Electrolysis of Dilute Sulfuric Acid generates Hydrogen and Oxygen gasses through oxidation and reduction reactions.

Hydrogen gas generated through this process can be used in various applications, such as fuel cells for clean energy production. 

Oxygen is used in medical and industrial applications, including welding and cutting.

Safety precautions should include using appropriate protective gear, working in a well-ventilated area, and handling chemicals and electrical equipment with care. Potential hazards include the corrosive nature of sulfuric acid, the flammability of hydrogen gas, and the need to avoid mixing with incompatible substances.