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8.把三氯化铁溶液蒸干灼烧,最后得到的固体产物是 (A)无水三氯化铁 (B)氢氧化铁 (C)氧化亚铁 (D)三氧化二铁错例1 错选A。简析:考生单纯从溶液蒸发的角度考虑,认为三氯化铁溶液蒸干灼烧最后得到的固体产物是无水三氯化铁。没有考虑到三氯化铁是强酸弱碱的盐,它在水溶液中全发生水解反应: FeCl_2+3H_2O Fe(OH)_3+3HCl 加热蒸发有利水解反应的进行,在蒸发灼烧过程中生成的HCl挥发。Fe(OH)_3灼烧会发生分解反应:2Fe(OH)_3 Fe_2O_3+3H_2O 因此FeCL_3溶液蒸于灼烧,最后得到的固体产物是Fe_2O_3,而不是无水三氯化铁。
8. The ferric chloride solution was evaporated to dryness and the final solid product was (A) anhydrous ferric chloride (B) iron hydroxide (C) ferrous oxide (D) iron oxide error 1 Mistake A. Analysis: From the perspective of solution evaporation, the examiner thought that the ferric chloride solution was evaporated to dryness and the resulting solid product was anhydrous ferric chloride. It is not considered that ferric chloride is a salt of a strong acid and a weak base. It fully hydrolyzes in an aqueous solution: FeCl 2 +3H 2 O Fe(OH) 3+3HCl Heating and Evaporation Advantageous hydrolysis reaction proceeds, HCl generated during evaporative ignition Volatilize. The decomposition reaction of Fe(OH)_3 is decomposed: 2Fe(OH)_3Fe_2O_3+3H_2O. So the solution of FeCL_3 is steamed and the final solid product is Fe_2O_3 instead of anhydrous ferric chloride.