orthophosphoricadj.
/ˌɔːθə(ʊ)fɒsˈfɒrɪk/, U.S. /ˈˌɔrθoʊˌfɑsˈfɔrɪk/ Chemistry.
orthophosphoric acid n. the tribasic acid H3PO4, a crystalline acid obtained e.g. by treating phosphates with sulphuric acid, and used in fertilizer and soap manufacture and food processing. Cf. phosphoric acid n. at phosphoric adj. Compounds.
ΚΠ
1864 Proc. Royal Soc. 1863–4 13 528 In order to study this reaction more closely, the experiment was repeated, substituting..common orthophosphoric for the ethylphosphoric [acid].
1873 H. Watts Fownes's Man. Elem. Chem. (ed. 11) 225 The aqueous solution..deposits orthophosphoric acid in prismatic crystals.
1906 H. J. H. Fenton Notes Qualitative Anal. (new ed.) 29 Orthophosphoric acid in solution may behave either as a mono-, di- or tri-basic acid according to concentration and other circumstances.
1952 W. H. Waggaman Phosphoric Acid, Phosphates & Phosphatic Fertilizers (ed. 2) i. 13 To the chemical manufacturer and distributor phosphoric acid means orthophosphoric acid.
1976 J. A. von Fraunhofer Basic Metal Finishing xiii. 146 The simplest phosphating treatment is immersion in hot dilute orthophosphoric acid solution for up to 30 min.
2001 Herald (Glasgow) (Nexis) 27 Mar. 9 West of Scotland Water says..orthophosphoric acid is added to prevent lead from the pipes dissolving into the water.
This entry has been updated (OED Third Edition, September 2004; most recently modified version published online March 2022).
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adj.1864