Triphosphoric acid

Triphosphoric acid (also tripolyphosphoric acid), with formula H5P3O10, is a <a href="/facts/Condensation_(chemistry)/wMG0F6La">condensed</a> form of <a href="/facts/Phosphoric_acid/l6NbwyCv">phosphoric acid</a>. In the family of <a href="/facts/Phosphoric_acids_and_phosphates/jAvA75lM">phosphoric acids</a>, it is the next <a href="/facts/Polyphosphoric_acid/jAvA75lM">polyphosphoric acid</a> after <a href="/facts/Pyrophosphoric_acid/QH7FqE52">pyrophosphoric acid</a>, H4P2O7, also called diphosphoric acid.
Compounds such as ATP (<a href="/facts/Adenosine_triphosphate/nB9bwgcU">adenosine triphosphate</a>) are <a href="/facts/Ester/FoUAIIw4">esters</a> of triphosphoric acid.
Triphosphoric acid has not been obtained in crystalline form. The equilibrium mixture with an overall composition corresponding to H5P3O10 contains about 20% of triphosphoric acid. A solution of the pure species can be obtained by ion exchange of the sodium salt, <a href="/facts/Sodium_triphosphate/0tWU3U9U">sodium triphosphate</a>, at 0 °C.
Triphosporic acid is a <a href="/facts/Pentaprotic_acid/FySU18n1">pentaprotic acid</a>, meaning that it can release five protons in basic enough conditions. Sources differ on the corresponding pKa values: 

<ul><li>1.0; 2.2; 2.3; 5.7; 8.5</li>
<li>1.0; 2.2; 2.3; 3.7; 8.5</li>
<li>small; small; 2.30; 6.50; 9.24</li></ul>

Triphosphoric acid open-in-new

Triphosphoric acid