## 从“验证模式”到“辩证模式”的转变——进一步增强高校本科生实验创新能力

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## Change from "Validation Mode" to "Dialectical Mode": to Further Enhance Experimental Innovation of Undergraduates

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 基金资助: 山东省高等学校科技计划项目.  J16LC05山东省青年自然科学基金.  ZR2016BQ20

 Fund supported: 山东省高等学校科技计划项目.  J16LC05山东省青年自然科学基金.  ZR2016BQ20

Abstract

In order to further enhance experimental innovation of the undergraduates, the "verification model" in laboratory courses should be changed urgently. How to improve and develop the undergraduate laboratory courses has become an important direction of the laboratory teaching mode for university teachers. The students are easier to observe and understand the nature and core of the experiment by changing the experimental conditions and dialectically viewing of experimental problems. This kind of "dialectical view" is a good developing trend. We will apply this kind of model to the experiment of preparation of ammonium ferrous sulfate and semi-quantitative analysis of iron (Ⅲ). The students can deeply discuss the differences in the experimental results by controlling the synthesis conditions. The different colored and sized of crystalline in turn can stimulate students' interest. Practice shows that this teaching model is conducive to promoting students' ability of independent inquiry learning, to cultivate their dialectical experimental thinking, thus to enhance students' practical and innovative ability, and to improve their comprehensive quality. This model can be extended to other experiments.

Keywords： Validation mode ; Dialectical mode ; Ammonium ferrous sulfate

YIN Jie, DAI Jianrong, XIONG Shixian, QIAO Yanling, ZHOU Huawei. Change from "Validation Mode" to "Dialectical Mode": to Further Enhance Experimental Innovation of Undergraduates. University Chemistry[J], 2018, 33(3): 21-26 doi:10.3866/PKU.DXHX201708016

## 1 “辩证模式”实验课堂的实施

${{\rm{Fe + }}{{\rm{H}}_{\rm{2}}}{\rm{S}}{{\rm{O}}_{\rm{4}}}{\rm{ + 7}}{{\rm{H}}_{\rm{2}}}{\rm{O = FeS}}{{\rm{O}}_{\rm{4}}} \cdot {\rm{7}}{{\rm{H}}_{\rm{2}}}{\rm{O + }}{{\rm{H}}_{\rm{2}}}{\rm{}}}$

${{\rm{FeS}}{{\rm{O}}_{\rm{4}}}{\rm{ + }}{{\left( {{\rm{N}}{{\rm{H}}_{\rm{4}}}} \right)}_{\rm{2}}}{\rm{S}}{{\rm{O}}_{\rm{4}}}{\rm{ + 6}}{{\rm{H}}_{\rm{2}}}{\rm{O = }}{{\left( {{\rm{N}}{{\rm{H}}_{\rm{4}}}} \right)}_{\rm{2}}}{\rm{Fe}}{{\left( {{\rm{S}}{{\rm{O}}_{\rm{4}}}} \right)}_{\rm{2}}} \cdot {\rm{6}}{{\rm{H}}_{\rm{2}}}{\rm{O}}}$

${{\rm{F}}{{\rm{e}}^{{\rm{3 + }}}}{\rm{}} + n{\rm{SC}}{{\rm{N}}^ - } = {\rm{ Fe}}{{\left[ {{{\left( {{\rm{SCN}}} \right)}_n}} \right]}^{3 - n}}(血红色)}$

 盐 溶解度(g/100 g H2O) 273.16 K 283.16 K 293.16 K 303.16 K 313.16 K 323.16 K 333.16 K FeSO4∙7H2O 15.6 20.5 26.5 32.9 40.2 48.6 (NH4)2SO4 70.6 73.0 75.4 78.0 81.0 88.0 (NH4)2Fe(SO4)2∙6H2O 12.5 33.0 40.0

### 图2

(a)缓慢结晶条件下抽滤前；(b)快速结晶条件下抽滤前；(c)氧化结晶条件下抽滤前；(d)缓慢结晶条件下抽滤后；(e)快速结晶条件下抽滤后；(f)氧化结晶条件下抽滤后

 分组 探索条件 实验现象 样品形态(形状、大小、颜色) 产率 纯度分析 第一组 小火加热，不搅拌，防止沸腾，慢速冷却 有透明感 颜色为蓝绿色，晶体颗粒较大，比较明显，亮度光泽比较好 高 纯度高，含有极少量氧化了的三价铁 第二组 小火加热，不搅拌，防止沸腾，快速冷却 有透明感 颜色为暗绿色，晶体颗粒较小，亮度光泽度较差 中 纯度较高，含有部分氧化了的三价铁 第三组 大火加热，搅拌，沸腾 不透明感 颜色近乎白色，结晶几乎近粉末状 低 纯度低，含有大量三价铁

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