现行高中化学课本(甲种本)第二册161页,有这么一道习题:“浸在水里的铁柱,与水面接触的部分比在水下的部分容易腐蚀。”我认为此题提法欠妥。首先必须明确,所谓金属的腐蚀,就是金属与介质作用失去电子而被氧化的过程。教材指出:电化腐蚀与化学腐蚀同时发生,但电化腐蚀普遍得多,是金属腐蚀的主要原因。那么,钢铁发生电化腐蚀时,究竟何处最容易腐蚀?我们知道,钢铁发生的电化腐蚀一般是吸氧腐蚀,如将铁柱放在水中:负(或阳)极:Fe-2e=Fe~(2+)(氧化反应)正(或阴)极:H_2O+(1/2)O_2+2e=2OH~-(还原反应)可见,在正极附近的水溶液中,〔OH~-〕增加,而且水溶液中 O_2的溶解量越多,则正极 In the current high school chemistry textbook (A kind), Book 2, page 161, there is such an exercise: “The iron column that is immersed in water is more likely to be in contact with the water than in the underwater part.” I think this question is Defective. First of all, it must be made clear that the so-called metal corrosion is the process by which the metal and the medium lose their electrons and are oxidized. The textbook points out that galvanic corrosion and chemical corrosion occur simultaneously, but galvanic corrosion is much more common and is the main cause of metal corrosion. Then, when steel is galvanically corroded, where is the easiest to corrode? We know that the galvanic corrosion that occurs in steel is generally oxygen corrosion, such as placing iron pillars in water: negative (or positive) pole: Fe-2e = Fe~ (2+) (Oxidation reaction) Positive (or negative): H 2 O + (1/2) O 2 + 2 e = 2 OH - (reduction reaction) is visible, in the aqueous solution near the positive electrode, [OH - -] increases, and the aqueous solution The more dissolved O_2, the more positive