探究锌与硫酸亚铁置换反应中无气泡产生的演示实验方案  

Inquiry on Experimental Scheme of No Bubble Generation in Intermetallic Replacement Reaction Between Zn and FeSO_(4)

作　　者：蒋大川 邓逸晨 苏林 李胜 张艳华[1] 伏劲松[1] 龙堵火 JIANG Da-Chuan;DENG Yi-Chen;SU Lin;LI Sheng;ZHANG Yan-Hua;FU Jin-Song;LONG Du-Huo(College of Chemistry and Materials Science,Sichuan Normal University,Chengdu 610068,China;Puming Middle School in Mianyang,Mianyang 621000,China;Dujiangyan Wanhui School,Dujiangyan 611800,China;JinyangMiddleSchool,Liangshan616250,China)

机构地区：[1]四川师范大学化学与材料科学学院,四川成都610068 [2]四川省绵阳普明中学,四川绵阳621000 [3]都江堰市万汇学校,四川都江堰611800 [4]凉山州金阳中学,四川金阳616250

出　　处：《化学教育（中英文）》2023年第7期105-108,共4页Chinese Journal of Chemical Education

基　　金：四川省教育厅重点项目“中学化学‘实’‘人’对话实验学习法研究及应用”(项目编号:18SA0201)。

摘　　要：初中化学教材中Zn置换Fe^(2+)中Fe的演示实验中产生的大量气泡干扰学生对置换反应的认知学习。造成该现象的原因主要有:(1)Zn置换出Fe后形成Zn-Fe原电池引起的析氢腐蚀;(2)Fe的析氢过电势较Zn低,因此Zn置换出的Fe掺杂后,使得析氢过电势降低产生大量的气泡。基于此,采取控制反应条件,抑制反应中气泡的产生、放大Zn置换Fe的现象。通过调整反应时Fe^(2+)的浓度、pH从而调整Zn-Fe原电池的数量以及析氢过电势,对该教学演示实验条件进行探究。结果表明当FeSO_(4)的浓度为0.54 mol/L、pH=3.58,Fe^(3+)的浓度在KSCN检测不出的条件下,可以观察到Zn置换出的Fe附着在Zn的表面且能被磁铁吸引,同时观察不到气泡的产生。A large number of bubbles generated in the demonstration experiment of Zn replacement of Fe in Fe^(2+)in junior high school chemistry textbooks interferes with students'cognitive learning of replacement reaction.The main reasons for this phenomenon are(1)the hydrogen evolution corrosion caused by the formation of Zn-Fe primary batteries after the replacement of Fe;(2)the hydrogen evolution potential of Fe is lower than that of Zn,so after Zn is displaced with Fe,the hydrogen evolution overpotential is reduced to produce a large number of bubbles.Based on this,the reaction conditions are controlled,the generation of bubbles in the reaction is inhibited,and the phenomenon of Zn displacing Fe is amplified.By adjusting the Fe2+concentration and pH during the reaction to adjust the number of Zn-Fe primary cells and the hydrogen evolution overpotential,the conditions of this teaching demonstration experiment are explored.The results show that when the concentration of FeSO_(4) is 0.54 mol/L,pH=3.58,and the concentration of Fe^(3+)cannot be detected by KSCN,the Fe displaced by Zn can be observed to be attached to the surface of Zn and can be attracted by magnets,and the generation of bubbles cannot be observed.

关 键 词：Zn与Fe^(2+)的置换反应 实验条件探究 无气泡产生 演示实验 

分 类 号：G633.8[文化科学—教育学]