Nitrogen preparation

Professor of physics at Cavendish Laboratory, Cambridge. He made elaborate investigations of the electrochemical equivalent of silver and of the combining volumes and compressibilities of gases. His observation that nitrogen prepared from the atmosphere is heavier than nitrogen prepared from ammonia led to the discovery of argon, the first noble gas. He also contributed to optics and acoustics. 

Assemble an arrangement as shown in Fig. 76 and check its tightness. Spill 1-2 g of triturated sodium nitrite into the test tube, pour in dropwise 2-3 ml of a concentrated ammonium chloride solution, and carefully (why ) heat the mixture. Collect the evolving gas and see whether it supports combustion. Write the equation of the reaction of nitrogen preparation. 

Carefully add the sodium metal (1.4 g, 61 mmol) to a double-necked round-bottomed flask, equipped with an addition funnel, a stirrer and a glass stopper, containing dry ethanol (150 mL), maintained under a gentle stream of nitrogen. Prepare a solution of diethyl malonate (20 g, 125 mmol) in dry ethanol (50 mL) and transfer this solution to the addition funnel. 

Oxygen-free nitrogen (prepared by flushing commercial gas over hot, reduced copper mesh or by passage through an oxygen trap). 

Finally, it should be noted that hydroquinone poses a serious galenical problem, as it tends to oxidize quickly preparations containing hydroquinone have to be mixed and packaged in an oxygen-free atmosphere (in nitrogen). Preparations packaged in jars oxidize too quickly and lose most of their effectiveness within a few days. The ideal packaging for hydroquinone cream is a hermetically sealed, double-layer, aluminum tube. 

Rayleigh was making exact measurements of the densities of gases and in 1892 found a curious result with nitrogen. Nitrogen prepared, at Ramsay s suggestion, by passing a mixture of air and ammonia over red-hot copper was... 

Further investigations showed that nitrogen prepared entirely from air... 

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