Inorganic Salts & Metal Compounds

Monoammonium phosphate (MAP, NH4H2PO4) is commonly graded 11-52-0, about 11% nitrogen and 52% P2O5, and gives an acidic solution of about pH 4 to 4.5. Diammonium phosphate (DAP, (NH4)2HPO4) is commonly 18-46-0 and gives a mildly alkaline solution of about pH 7.5 to 8. DAP carries more nitrogen per tonne, while MAP releases less free ammonia as it dissolves, which suits alkaline soils and placement close to seed.

Quicklime is calcium oxide (CaO), made by calcining limestone. It reacts vigorously with water, releasing heat, to form hydrated lime, calcium hydroxide (Ca(OH)2), a dry fine powder. Quicklime is chosen where that reactivity is useful, such as steelmaking fluxes and AAC blocks. Hydrated lime is easier and safer to dose, so it is the usual form for water softening, effluent pH correction, building mortars and leather liming.

Both supply the same zinc; the difference is water of crystallisation. Zinc sulphate heptahydrate (ZnSO4·7H2O) typically carries about 21% zinc and the monohydrate (ZnSO4·H2O) about 33%, so the monohydrate needs less material, freight and storage space for the same zinc dose. Fertiliser, feed and industrial specifications state the minimum zinc content they require, and that figure decides which form and grade to order.

Chrome tanning uses trivalent chromium, normally as basic chromium sulphate (BCS). Commercial tanning grades are commonly around 33% basicity with about 25% Cr2O3, and they convert pickled hides into wet blue leather. Chromic acid and sodium or potassium dichromate contain hexavalent chromium; they are used for chrome plating, oxidation and as feedstocks rather than for direct tanning, and are handled under stricter hazardous chemical controls.

Borax decahydrate (Na2B4O7·10H2O) contains about 11.3% boron and brings sodium with it; boric acid (H3BO3) contains about 17.5% boron and no sodium. Uses that must limit sodium, such as E-glass fibre, and nickel plating baths, where boric acid acts as a buffer, normally take boric acid. Ceramic glazes, detergents, metal fluxes and boron micronutrient fertilisers often use borax. Potassium tetraborate is the option for sodium-free brazing fluxes.

Yes, for industrial uses such as lead-acid batteries, lead glass and frits, plating and metal finishing. Lead compounds and hexavalent chromium salts are supplied subject to regulatory compliance, packed and hazard-labelled to rule, with the manufacturer's COA and SDS for each batch. Note that Indian rules cap lead in household and decorative paints at 90 ppm, so lead compounds are not an option for those paints.