phosphorous acid

noun Chemistry.

1. a colorless, crystalline, water-soluble acid of phosphorus, H3PO3, from which phosphites are derived.

noun

1. Also called: orthophosphorous acid a white or yellowish hygroscopic crystalline dibasic acid. Formula: H 3 PO 3Systematic name: phosphoric acid
2. any oxyacid of phosphorus containing less oxygen than the corresponding phosphoric acid

1. A white or yellowish crystalline solid used as a reducing agent. It is hygroscopic (easily absorbs moisture from the atmosphere). Chemical formula: H3PO3.