Industrial Uses of Common Substances

Overview

• Lesson covers applied science Unit 5 topic: uses of substances in industry.
• Focus areas: calcium hydroxide in effluent treatment, alumina in refractories, and uses of transition metals and their compounds as catalysts.
• Definitions and industrial examples are provided for key processes.

Effluent Treatment With Calcium Hydroxide

• Effluent: liquid waste discharged into rivers and streams by factories.
• Problem: many industries use sulfuric acid, producing acidic effluents that lower water pH and damage the environment.
• Solution: neutralization using a base.
• Reaction: calcium hydroxide (a metal hydroxide base) neutralizes sulfuric acid to form calcium sulfate and water.
• Purpose: raises pH of effluent, reducing environmental harm.

Alumina (Aluminium Oxide) in Refractories

• Refractory material: stable physically and chemically at very high temperatures.
• Alumina: aluminium oxide, formula Al2O3.
• Properties:
  • Maintains mechanical strength at high temperatures.
  • Chemically and physically stable under heat.
  • Very high melting point.
• Uses:
  • Lining furnaces.
  • Components in chemical reactors.
• Reason: stability and high melting point make alumina suitable where materials face extreme heat.

Transition Metals and Catalysts — Definitions

• Catalyst: increases reaction rate without being permanently used up; may be temporarily changed but regenerated by reaction end.
• Activation energy: minimum energy required for colliding particles to react successfully.

Why Transition Metals Make Good Catalysts

• Multiple oxidation states enable electron transfer and redox participation.
• Provide alternative reaction pathways with lower activation energies.
• Allow industrial reactions at lower temperatures, saving energy and reducing production costs.
• Can act by:
  • Undergoing reversible chemical changes (homogeneous or heterogeneous catalysis).
  • Providing surfaces for reactant adsorption, weakening bonds and facilitating reaction.

Industrial Examples of Transition Metal Catalysts

• Vanadium Oxide (V2O5) — Contact Process for Sulfuric Acid:
  • Contact process stages: burn sulfur to SO2; oxidize SO2 to SO3 (reversible); form fuming sulfuric acid with SO3; add water to produce H2SO4.
  • V2O5 acts as the catalyst in SO2 → SO3 step.
  • Catalyst cycle: V2O5 is reduced to V2O4 during reaction, then re-oxidized to V2O5, so catalyst is regenerated.
  • Importance: speeds up the reversible oxidation step, increasing SO3 yield at industrial scale.

• Iron — Haber Process for Ammonia:
  • Haber process produces NH3 from N2 and H2 for fertilizer production.
  • Iron catalyst provides a surface for N2 and H2 adsorption; bonds in reactants weaken on the surface.
  • Effect: lowers activation energy, enabling ammonia formation under industrial conditions.
  • Importance: increased crop yields via fertilizers.

• Catalytic Converters — Platinum, Palladium, Rhodium:
  • Located on exhaust of internal combustion engines.
  • Convert pollutants to less harmful gases: CO and NOx → CO2 and N2.
  • Use precious transition metals: platinum, palladium, rhodium.
  • Legal requirement: cars must be fitted with catalytic converters to reduce emissions.

Key Terms and Definitions

• Effluent: liquid industrial waste discharged into water.
• Refractory: material stable physically and chemically at very high temperatures.
• Alumina: aluminium oxide, Al2O3, used in refractory applications.
• Catalyst: substance increasing reaction rate without net consumption.
• Activation Energy: minimum energy needed for reacting particles to successfully collide.

Action Items / Next Steps

• Review previous three videos referenced for background on these topics.
• Memorize definitions: effluent, refractory, catalyst, activation energy.
• Understand the role of catalysts in reducing activation energy and industrial energy costs.
• Learn the industrial examples and the catalysts used: V2O5 (Contact), Fe (Haber), Pt/Pd/Rh (Catalytic converters).