Real-World Applications

Application	Concept Used	Details
Haber Process (Ammonia synthesis)	Stoichiometry, limiting reagent	$N_{2}$ + 3 $H_{2}$ --[Fe catalyst, 400–500 °C, 150–300 atm]--> 2 $NH_{3}$ ; mole ratios control raw material costs
Drinking water treatment	ppm concentration	Fluoride added at 0.7–1.0 ppm; chlorine at 0.2–0.5 ppm for disinfection
IV saline bags (medicine)	Molarity	0.9% NaCl (w/v) = 0.154 M NaCl; isotonic with blood plasma
Blood alcohol level testing	Molarity / density	Measured in mg/100 mL (mass/volume ratio); legal limit typically 80 mg/100 mL
Antacid tablets	Acid-base stoichiometry, n-factor	Each $CaCO_{3}$ (M = 100) molecule neutralises 2 moles of HCl; normality calculations key
Fertiliser industry	% composition	Urea CO(N $H_{2}$ )_{2}: 46.7% N by mass — highest nitrogen content of solid fertilisers
Quality control in pharma	Normality, titration	Active ingredient purity verified by standardised acid-base or redox titrations
Cement production	Law of Conservation of Mass	$CaCO_{3}$ → CaO + $CO_{2}$ ; mass loss of 44/100 = 44% of $CaCO_{3}$ mass as $CO_{2}$

Oral rehydration salts (ORS): Precise molar concentrations of NaCl and glucose are critical — deviations of even 10–20 mOsm/L can be dangerous.
Drug dosing: Molarity and molality are used to calculate dosing in mg/kg body weight from stock solution concentrations.