Some Basic Concepts in Chemistry: Industrial & Real-world Applications

Haber Process (Ammonia synthesis): $N_{2}$ + 3 $H_{2}$ --[Fe, 400–500 °C, 150–300 atm]--> 2 $NH_{3}$ . Stoichiometry and limiting reagent principles control raw material efficiency and industrial cost optimisation.
Drinking water treatment: Fluoride added at 0.7–1.0 ppm for dental health; chlorine at 0.2–0.5 ppm for microbial disinfection. Both concentrations use ppm (mg/L), directly applying the concentration concepts in this chapter.
Intravenous saline: Normal saline = 0.9% NaCl (w/v) = 0.154 M NaCl — isotonic with blood plasma. Incorrect molarity in IV fluids causes cell lysis or crenation — a medical emergency.
Oral rehydration salts (ORS): WHO formula requires precise molar concentrations of NaCl and glucose. Small deviations in osmolarity are clinically dangerous.
Antacids ( $CaCO_{3}$ , Al(OH)_{3}): Stoichiometry of acid neutralisation (n-factor, equivalents) governs the dose required to neutralise stomach acid.
Urea as fertiliser: CO(N $H_{2}$ )_{2} has 46.7% N by mass — calculated using percentage composition formula. Highest nitrogen content of any solid fertiliser.
Blood alcohol content (BAC): Expressed as mg of ethanol per 100 mL blood. Legal driving limit in India: 30 mg/100 mL. Directly uses mass/volume concentration concepts.
Cement production: $CaCO_{3}$ --[heat]--> CaO + $CO_{2}$ . Mass loss = 44/100 = 44% ( $CO_{2}$ expelled). Law of conservation of mass and stoichiometry govern kiln yield calculations.
Pharmaceutical titration: Purity of active ingredient determined by standardised acid-base or redox titrations using normality and equivalent weight — core applied use of n-factor.
Environmental monitoring: $CO_{2}$ in atmosphere (~415 ppm), $NO_{2}$ threshold (40 μg/ $m^{3}$ ), lead in water (<10 ppb). All use trace concentration units from this chapter.