Calcium hydride Subject

Other methods that have been used in determination of the amount of moisture in coke include (1) extraction of coke using anhydrous methanol and the addition of calcium hydride with coal constituents (CaH2) from which the amount of released heat is measured, and (2) extraction of coke using anhydrous dioxan and measurement of the refractive index of the solution to determine its water content. Application of these methods to coal may be subject to error because of (1) interaction of the coal (in contrast to coke) with the calcium hydride, leading to chemical errors, and (2) the influence of extractable constituents on the refractive index of the dioxan. 

Acetonitrile is hygroscopic and also prone to hydrolytic decomposition. Hence, in addition to water, it virtually always contains acetamide, ammonia and possibly ammonium acetate as impurities. It cannot be dried with potassium hydroxide, since this would catalyze the hydrolysis. A molecular sieve with a pore size of 0.4 nm has proved effective for the drying of acetonitrile. Following treatment with this, the solvent is subjected to fractional distillation. Application of the molecular sieve makes unnecessary the previously employed treatment with calcium hydride and phosphorus pentoxide. 

Perchlorates are powerful oxidizing substances. These compounds explode when mixed with combustible, organic, or other easily oxidizable compounds and subjected to heat or friction. Perchlorates explode violently at ambient temperatures when mixed with mineral acids, finely divided metals, phosphorus, trimethylphosphite, ammonia, or ethylenediamine. Explosions may occur when perchlorates are mixed with sulfur, or hydride of calcium, strontium, or barium and are subjected to impact or ground in a mortar. Perchlorates react with fluorine to form fluorine perchlorate, an unstable gas that explodes spontaneously. Heating perchlorates to about 200°C (392°F) with charcoal or hydrocarbons can produce violent explosions. Metal perchlorates from complexes with many organic solvents, which include benzene, toluene, xylenes, aniline, diozane, pyridine, and acetonitrile. These complexes are unstable and explode when dry. Many metal perchlorates explode spontaneously when recrystaUized from ethanol. Saturated solution of lead perchlorate in mathanol is shock sensitive. 

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