Chemistry in life: responsible choices
Chemistry connects molecular structure to material performance, process efficiency, exposure control, food quality, and recovery after use.
Learning goals. Compare material families; calculate yield and atom economy; explain catalyst and energy tradeoffs; use life-cycle thinking; distinguish hazard, exposure, and risk; apply chemistry to packaging, storage, contamination control, and responsible disposal.
1. Select materials by evidence
| Family | Typical strengths | Typical limitations |
|---|---|---|
| Metals and alloys | strength, toughness, conductivity, formability | corrosion, density, energy-intensive primary production |
| Polymers | low density, insulation, chemical resistance, easy shaping | temperature limits, aging, permeability, sorting challenges |
| Ceramics and glass | hardness, heat and chemical resistance, compression strength | brittleness and difficult joining |
| Composites | properties tailored by combining phases | repair, separation, and recycling may be difficult |
A responsible specification includes required lifetime, load, temperature, electrical behavior, chemical compatibility, barrier performance, maintenance, repairability, mass, and end-of-use route. No family is universally “best”; performance must match the function.
2. Process chemistry: more than percentage yield
Yield
Percentage yield = actual desired product / theoretical desired product × 100%. It measures how much desired product was recovered.
Atom economy
Atom economy = formula mass of desired product / total formula mass of stoichiometric reactants × 100%. It asks where reactant atoms go.