Phosphates with Chain Anions. The Polyphosphates

Condensed Phosphates with Chain Anions. The Polyphosphates 

The polyphosphates include all compounds with the composition Mei[+2PnOaB+i, or MenIH2Pn03n+I. The first members are the dihydrogen monophosphates, Me HsPCh, which are stable and go over into members of the series with higher molecular weight by condensation. Their anions are chain-like. 

The free acids carry a strongly dissociated acid OH group on each phosphorus atom and each of the two ends of the chain has a weakly dissociated 

OH group. Solutions of their neutral alkali salts, therefore, have a weakly alkaline reaction, while the acid salts in which the terminal OH groups arc not replaced by cations, are weakly acid. 

Pyro- and di-phosphates, the simplest members of the group of condensed phosphates, are so well known that only the results of recent investigations will be described here, and only in so far as they bear on the chemistry of condensed phosphates. Thus, ever since Clark s investigations 52), it has been common knowledge among chemists that diphosphates arc obtained by heating monohydrogen phosphates, or by double decomposition of other diphosphates. It was unexpected, however, to find that an equilibrium 

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IV. Condensed Phosphates with Chain Anions. The Polyphosphates. 23... 

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