Definitions and terminology

1. The Chlor-Alkali Industry

• A global industry that electrolyses sodium chloride $(NaCl)$ solutions to produce:
  • Chlorine gas $(Cl_₂)$
  • Hydrogen gas $(H_₂)$
  • Sodium hydroxide $(NaOH) (aq)$

2. Key Processes

Electrolysis

• Endothermic reaction – requires electrical energy.
• Converts electrical energy into chemical energy.
• A non-spontaneous redox reaction (does not occur naturally).

Oxidation

• Loss of electrons.
• Occurs at the anode (positive electrode).

Reduction

• Gain of electrons.
• Occurs at the cathode (negative electrode).

3. Important Terminology

• Corrosive: A substance that damages or destroys materials (e.g., chlorine gas).
• Leaching: Movement of dissolved substances (e.g., $NaCl$ solution, fertilisers, pesticides) through soil into groundwater.
• Carbon footprint: The total amount of $CO_₂$ and other greenhouse gases released into the atmosphere due to human activities.
• Brine: A concentrated $NaCl$ solution, used as the electrolyte in the chlor-alkali process.

4. Key Takeaways

• The Chlor-Alkali industry relies on the electrolysis of brine.
• Oxidation occurs at the anode, while reduction occurs at the cathode.
• Important environmental terms include corrosion, leaching, and carbon footprint.