phosphorous acid

American  

noun

Chemistry.

1. a colorless, crystalline, water-soluble acid of phosphorus, H 3 PO 3 , from which phosphites are derived.

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phosphorous acid British  

noun

1. Systematic name: phosphoric acid.  Also called: orthophosphorous acid.  a white or yellowish hygroscopic crystalline dibasic acid. Formula: H 3 PO 3

2. any oxyacid of phosphorus containing less oxygen than the corresponding phosphoric acid

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phosphorous acid Scientific  

/ fŏs′fər-əs,fŏs-fôr′əs /

1. A white or yellowish crystalline solid used as a reducing agent. It is hygroscopic (easily absorbs moisture from the atmosphere). Chemical formula: H ₃ PO ₃ .

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Etymology

Origin of phosphorous acid

First recorded in 1785–95

Example Sentences

The best method for preparing pure phosphorous acid is by hydrolyzing phosphorus trichloride:

From Textbooks • Feb. 14, 2019

Like most other nonmetal halides, both phosphorus chlorides react with an excess of water and yield hydrogen chloride and an oxyacid: PCl3 yields phosphorous acid H3PO3 and PCl5 yields phosphoric acid, H3PO4.

From Textbooks • Feb. 14, 2019

Write equations showing the stepwise ionization of phosphorous acid.

From Textbooks • Feb. 14, 2019

When sufficient water evaporates, white crystals of phosphorous acid will appear upon cooling.

From Textbooks • Feb. 14, 2019

I distilled two parts of finely pulverised manganese with one part of the phosphorous acid of urine in the same way as is indicated in the preceding paragraph, I likewise obtained fire-air.

From Discovery of Oxygen, Part 2 by Scheele, Carl Wilhelm