The Halogens and Atom Economy

The Halogens and Atom Economy

The Halogens

  • The term halogen describes a group of five nonmetallic elements in Group 7 of the periodic table: fluorine, chlorine, bromine, iodine, and astatine.
  • Halogens typically gain one electron to achieve a full outer shell of electrons, making them highly reactive.
  • Reactions with halogens often result in ionic compounds, where the halogen gains the electron it needs to complete its outer shell, forming a negative ion called a halide.
  • Displacement reactions of halides: A more reactive halogen gas will displace a less reactive halide from a salt solution of that halide. For example, Cl2 (g) + 2NaI (s) –> 2NaCl (s) + I2 (g), where chlorine gas displaces iodide ions.
  • Halogen-halide solution reactions: Colour changes in reactions with halogens can be used for identification. Chlorine water colours bromide solution brown (forming bromine) and iodide solution purple (forming iodine). Bromine water colours iodide solution purple (forming iodine).
  • Extracting chlorine from sea water: Chlorine can be obtained from sea water through electrolysis. This is commonly done in the production of bleach and disinfectants.

Atom Economy

  • Atom economy is a measure of the amount of reactants that end up as useful products. It’s crucial in sustainable development as it helps us improve resource usage.
  • Efficiency is important in chemical reactions to reduce waste and ensure sustainability. The higher the percentage atom economy, the lower the waste and the more efficient the process.
  • The equation for atom economy is (Mass of desired product / Total mass of reactants) x 100%.
  • It’s important to maximize atom economy to reduce waste and make the process more financially viable, especially for industries.
  • Chemical reactions with high atom economy are more likely to be used on an industrial scale.
  • Some by-products of reactions can also be utilized commercially, improving the overall atom economy of the process.
  • Industrial processes must strive for 100% atom economy through better reaction designs, such as using reactants atomically or recyclable catalysts.

Remember, understanding the chemistry of the halogens is crucial in carrying out effective and efficient chemical processes, while atom economy plays a major role in sustainable chemistry, affecting both the environment and economy.