Liquid Ammonia - Elution Ammonia

This refers to liquid ammonia. It is also called liquid ammonia. Ammonia liquefies at -33°C under 1 atm and at 8.46 atm at 20°C. It has a large heat of vaporization (23.4 kJ (boiling point)) and is used as a cooling medium (refrigerant) by utilizing the cooling effect caused by adiabatic expansion. It has a large relative dielectric constant (25 (-78°C)) and is an ionizable solvent.

_2NH3NH4 ⁺⁺ _NH2-​^​

Although it ionizes as shown above, it is a weaker electrolyte than water, with an ionic product of [NH ₄ ⁺ ][NH ₂ ^- ] of 10 ^-22 mol ² dm ^-6 (-33 °C). It dissolves alkali metals to produce a blue solution, because the electrons generated by the ionization of the metal become solvated electrons. It dissolves polar substances well, but since its degree of ionization is smaller than that of water, it dissolves organic substances better than water. In liquid ammonia, ammonium salts become ammonoacids, and amide compounds become ammonobases. Just as with acids and bases in aqueous solutions, acid and base indicators also change color accordingly. Its proton affinity is greater than that of water, making it a strongly basic solvent, and strong reducing agents that reduce water will not reduce ammonia in liquid ammonia, making it possible to study the reduction reactions of strong reducing agents.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

液体状のアンモニアをいう．液安ともいう．アンモニアは1 atm 下では－33 ℃ で，20 ℃ では8.46 atm で液化する．蒸発熱が大きく(23.4 kJ(沸点))，断熱膨張による冷却効果を利用して，冷却用媒体(冷媒)に利用される．比誘電率が大きく(25(－78 ℃))，電離性溶媒で

2NH₃ NH₄^＋ ＋ NH₂^－

のように電離しているが，水よりは弱い電解質でイオン積[NH₄^＋][NH₂^－]は 10^－22 mol² dm^－6(－33 ℃)．アルカリ金属を溶かして青色液となるが，これは金属のイオン化によって生じた電子が溶媒和電子となるためである．極性物質をよく溶解するが，水より電離度が小さいため，水よりは有機物をよく溶かす．液体アンモニア中ではアンモニウム塩はアンモノ酸，アミド化合物はアンモノ塩基となる．これらに対しては，水溶液中の酸塩基と同様，酸・塩基指示薬もそれぞれに対応して変色する．陽子親和力は水より大きいので塩基性の強い溶媒であり，水を還元するような強い還元剤も液体アンモニア中ではアンモニアを還元することはなく，強還元剤の還元反応を研究することができる．

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