Sodium carbonate.mono-hydrate

Both mono- and disodium phosphates are prepared commercially by neutralization of phosphoric acid using sodium carbonate or hydroxide. Crystals of a specific hydrate can then be obtained by evaporation of the resultant solution within the temperature range over which the hydrate is stable. For the preparation of trisodium phosphate, sodium hydroxide must be used to reach the high end pH because CO2 cannot be stripped readily from the solution above a pH of near 8. 

Decomposition of model substances method The third method of calibration is by carrying out an experimental run using certain well studied model substances such as copper sulfate pentahydrate, calcium carbonate, calcium oxalate mono hydrate, potassium carbonate, sodium hydroxide, zinc oxalate dihydrate, and benzoic acid. These model substances show well resolved dehydration and decomposition temperatures over a wide temperature range. 

Potassium selenides.—The monoselenide, K2Se, is formed by the action of selenium on excess of potassium dissolved in liquid ammonia with excess of selenium the tetraselenide, KjSe is produced.3 Each compound resembles the corresponding sodium derivative. With solutions of potassium carbonate, hydrogen selenide reacts forming a number of hydrates of the monoselenide. The heat of formation of the anhydrous mono-derivative is given as 79-4 Cal.4 The triselenide has been isolated,5 and Fabre has also described the primary selenide, KSeH. 

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