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A white or yellowish hygroscopic crystalline solid, H3PO3, used as a reducing agent and to produce phosphite salts.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. (Elements & Compounds) Also called: orthophosphorous acid a white or yellowish hygroscopic crystalline dibasic acid. Formula: H3PO3. Systematic name: phosphoric acid
2. (Elements & Compounds) any oxyacid of phosphorus containing less oxygen than the corresponding phosphoric acid
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a colorless, crystalline, water-soluble acid of phosphorus, H3PO3, from which phosphites are derived.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.