Chemistry in Everyday Life
Applied chemistry underpins household substances, pharmaceutical agents, food preservation, and industrial manufacturing. Common household chemicals include sodium chloride (table salt), sodium bicarbonate (baking soda), sodium carbonate decahydrate (washing soda), and calcium hypochlorite (bleaching powder). The pH scale, formulated by Danish chemist S.P.L. Sørensen in 1909, measures hydrogen ion activity from 0 to 14, where human blood is maintained within a narrow alkaline buffer of 7.35 to 7.45. Synthetic detergents differ from soaps because their sulfonate groups do not form insoluble precipitates in hard water containing magnesium and calcium ions. Common food preservatives such as sodium benzoate prevent microbial spoilage by lowering intracellular pH.
Key Concepts & Examination Highlights
- S.P.L. Sørensen introduced the pH scale in 1909 to quantify the acidity or basicity of aqueous chemical solutions.
- Baking soda is chemically known as sodium hydrogen carbonate ($NaHCO_3$), whereas washing soda is sodium carbonate decahydrate ($Na_2CO_3\cdot 10H_2O$).
- Soaps are sodium or potassium salts of fatty acids, while detergents are alkylbenzenesulfonate salts that remain soluble in hard water.