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Chemistry

Industrial Chemistry

4,351 words, 11 sections

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Industrial chemistry explains how the materials people actually consume are made: the plastics, fibres, adhesives and dyes of everyday objects, and the bulk acids, alkalis, fertilizers and metals behind farms and factories. It sits in the chemistry paper, worth 45 of the 180 marks, and it carries 132 distinct questions across 58 official papers between 2001 and 2026, with a mean item difficulty of 1.57 and 690 active questions in the practice bank. Six boards set it (Balochistan, DUHS, Federal, KMU, NUMS and UHS), so none of it can be dropped. A student who knows which process makes what, how substances are classified, and which conditions a plant must use holds most of the marks.

Addition polymerisation joins monomers that carry a carbon to carbon double bond, and because the bond simply opens, nothing is expelled. Vinyl chloride heated at 60 to 70 °C with hydrogen peroxide gives polyvinyl chloride; polystyrene, polyethene and Teflon add the same way, polyethene needing 400 °C and 1000 atm with about 0.1 per cent oxygen and Teflon repeating the unit −(CF2−CF2)n−-(\text{CF}_2-\text{CF}_2)_n-. Polyvinyl acetate is a homopolymer of vinyl acetate, made from ethene and acetic acid over palladium(II) chloride.

Condensation polymerisation links two difunctional monomers and removes a small molecule, usually water. Hexamethylenediamine and adipic acid (hexanedioic acid) each carry six carbons, and the repeating amide linkage −NH−CO−-\text{NH}-\text{CO}- makes nylon-6,6 a polyamide; nylon-4,6 comes from hexanedioic acid and 1,4-diaminobutane. Terylene is a polyester of a dicarboxylic acid and a diol, repeating through an ester −CO−O−-\text{CO}-\text{O}-, and Bakelite is the cross-linked thermoset from phenol and formaldehyde. One monomer gives a homopolymer and two a copolymer; thermoplastics such as PVC remelt while thermosets set once; Perspex is the transparent plastic of combs.

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