答案,应选B、C。经过实验我们发现,装置D亦能产生电流。现定性分析如下。 我们知道,当把金属棒插入电解质溶液时,一方面,金属表面的一些原子有一种把电子留在金属表面而自身以离子形式进入溶液的倾向,金属愈活泼,溶液愈稀,这种倾向愈大;另一方面,溶液中的金属离子,又有一种从金属表面获得电子而沉积在金属表面的倾向,金属愈不活泼,溶液愈浓,这种倾向愈大。这样就在金属表面和溶液间产生了“双电层”,从而产生了电势。由于锌和铜活泼性不同,失电子的能力不同,同一电解质溶液对两金属的“浓度”也不 The answer should be B, C. Through experiments we have found that device D can also generate current. The qualitative analysis is as follows. We know that when inserting a metal rod into an electrolyte solution, on the one hand, some atoms of the metal surface have a tendency to leave electrons on the metal surface and enter the solution in an ionic form. The metal is more active and the solution becomes thinner. On the other hand, the metal ions in the solution have a tendency to get electrons from the metal surface and deposit on the metal surface. The less active the metal, the thicker the solution, the greater this tendency. This creates a “double layer” between the metal surface and the solution, creating a potential. Since the zinc and copper are different in their liveliness, the ability to lose electrons is different, and the same concentration of the electrolyte in the two metals is not