Lecture on Atom Economy in Chemical Reactions

Introduction

• Commercial Chemical Reactions: Typically produce multiple products.
• Focus on Desired Products: Aim is often to produce only one or two useful products, e.g., hydrogen in a reaction where carbon dioxide is a waste.

Atom Economy

• Definition: A measure to quantify the efficiency of a reaction in terms of the use of atoms from the reactants to the useful product.
• Equation:
  • (Relative Formula Mass of Desired Product / Total Relative Formula Mass of Reactants) x 100 = Atom Economy (%).

Calculation Example

• Desired Product: Hydrogen (H₂)
  • Relative Formula Mass (Mr) = 2 (1 for each hydrogen atom).
• Reactants: Carbon Monoxide (CO) and Water (H₂O)
  • Mr of CO = 28
  • Mr of H₂O = 18
• Total Mr of Reactants: 28 + 18 = 46
• Atom Economy Calculation:
  • (Mr of H₂ / Total Mr of Reactants) x 100 = (2/46) x 100 = 4.35%

Interpretation of Atom Economy

• Low Atom Economy: 4.35% indicates low efficiency; most reactants are waste.
• High Atom Economy Example:
  • Reaction of Nitrogen and Hydrogen to form Ammonia (NH₃)
  • Atom Economy = 100% (All reactants form the desired product).

Importance of Atom Economy

1. Cost Efficiency: Raw materials are expensive; converting them mostly into waste is less profitable.
2. Sustainability: Using large amounts of reactants for small product yields is unsustainable.
3. Environmental Impact: Waste products can be costly to dispose of and harmful to the environment.

Solutions to Improve Atom Economy

• Use Efficient Reactions: Find reactions with higher atom economies.
• Utilize Waste: Convert waste products into useful by-products.

Other Factors Influencing Reaction Profitability

• Percentage Yield: The actual yield versus theoretical yield.
• Cost of Raw Materials
• Equilibrium Position
• Rate of Reaction
• Cost of Maintaining Conditions: Temperature and pressure management.

Conclusion

• Consideration of atom economy is crucial for economic, environmental, and sustainable chemical manufacturing.
• Stay informed and apply strategies to improve reaction efficiencies.