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HPA is usually supplied as a 50% aqueous solution and heating at low temperatures (up to about 90 °C) prompts it to react with water to form phosphorous acid and hydrogen gas. H 3 PO 2 + H 2 O → H 3 PO 3 + H 2. Heating above 110 °C causes hypophosphorous acid to undergo disproportionation to give phosphorous acid and phosphine. [7] 3 H 3 PO ...
The general formula of a phosphoric acid is H n−2x+2 P n O 3n−x+1, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure; that is, the minimum number of bonds that would have to be broken to eliminate all cycles.
It reduces solutions of noble metal cations to the metals. When phosphorous acid is treated with a cold solution of mercuric chloride, a white precipitate of mercurous chloride forms: H 3 PO 3 + 2 HgCl 2 + H 2 O → Hg 2 Cl 2 + H 3 PO 4 + 2 HCl. Mercurous chloride is reduced further by phosphorous acid to mercury on heating or on standing:
The water molecule is amphoteric in aqueous solution. It can either gain a proton to form a hydronium ion H 3 O +, or else lose a proton to form a hydroxide ion OH −. [7] Another possibility is the molecular autoionization reaction between two water molecules, in which one water molecule acts as an acid and another as a base. H 2 O + H 2 O ...
[5] [6] [7] In the Brønsted–Lowry theory acids and bases are defined by the way they react with each other, generalising them. This is best illustrated by an equilibrium equation. acid + base ⇌ conjugate base + conjugate acid. With an acid, HA, the equation can be written symbolically as:
The standard Gibbs free energy of formation (G f °) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C).
Hydrogen phosphate or monohydrogen phosphate (systematic name) is the inorganic ion with the formula [HPO 4] 2-. Its formula can also be written as [PO 3 (OH)] 2-. Together with dihydrogen phosphate, hydrogenphosphate occurs widely in natural systems. Their salts are used in fertilizers and in cooking. [1]
Ammonium phosphomolybdate is the inorganic salt of phosphomolybdic acid with the chemical formula (NH 4) 3 PMo 12 O 40. The salt contains the phosphomolybdate anion, a well known heteropolymetalate of the Keggin structural class.