《卤素》实验中的若干问题解答

高一新教材《肉素》一章涉及到的实验较多，这些实验问题需要认真分析整理方能掌握．下面七个问题是最具代表性的。

联系实际 综合应用——《卤素》中的综合问题

(1)应用性综合：如以含氯元素的物质可作杀菌消毒剂为素材的试题，在近几年高考中出现的几率较大，包括二氧化氯(2003年上海，氧化还原计算)、漂粉精(2001年上海，成分判断)、一氯氨等。

《卤素》知识拾零

氯水是氯气的水溶液．通常情况下，2体积氯气溶于1体积水中可制得饱和氯水．溶解的氯气能够与水反应生成盐酸和次氯酸：Ch+H2O——HCl+HClO．新制的饱和氯水中只有大约39％的氯气与水反应，其余仍以Cl2分子的形式存在于溶液中．因此新制的氯水的成分为三分子四离子；即Ch、HClO、

Separation of halogens and recovery of heavy metals from secondary copper smelting dust

The separation of halogens and recovery of heavy metals from secondary copper smelting(SCS)dust using a sulfating roasting−water leaching process were investigated.The thermodynamic analysis results confirm the feasibility of the phase transformation to metal sulfates and to gaseous HF and HCl.Under the sulfating roasting conditions of the roasting temperature of 250℃ and the sulfuric acid excess coefficient of 1.8,over 74 wt.%of F and 98 wt.%of Cl were volatilized into flue gas.Approximately 98.6 wt.%of Zn and 96.5 wt.%of Cu in the roasting product were dissolved into the leaching solution after the water leaching process,while the leaching efficiencies of Pb and Sn were only 0.12%and 0.22%,respectively.The mechanism studies indicate the pivotal effect of roasting temperature on the sulphation reactions from various metal species to metal sulfates and the salting out reactions from various metal halides to gaseous hydrogen halides.

浅谈《卤素》一章的教学

在中学阶段的元素化学知识中,《卤素》占有极其重要的地位。教材编辑者把这一重要内容安排在高中化学课本(必修)的最开头,可谓独具匠心。笔者拟根据自己多年的教学实践,谈谈对《卤素》一章教学的认识和做法。

让研究性学习走进课堂教学——《卤素》教学新模式初探

一、问题的提出 一般意义上的研究性学习似乎与课堂教学没有很紧密的联系，学生也似乎更乐意选择与课堂教学不直接相关的课题进行研究。这未尝不可，但师生如果放弃了将研究性学习与课堂紧紧相连的大好时机，就大大浪费了一片广阔的、极具挖掘潜力的天地。

Adsorption of fluorine and chlorine on Mg(0001) surface:A density functional theory investigation

The adsorption of low-coverage of F and Cl adatoms on the Mg（0001） surface was investigated using first-principles calculations based on the density functional theory（DFT）.The stability of the（2×2） structures formed by halogen atoms adsorbed at different sites was determined.The difference between the adsorption of F and Cl on Mg（0001） surface was also discussed.The calculation results show that hollow sites are the energetically most favorable at the low-coverage.It can be concluded from the Mulliken charges and density of states that electrons transfer from the substrate Mg atoms to the adatoms,which leads to the formation of adsorbate bond and further causes the stronger interaction between Mg atom and adatom.The interaction between Cl and Mg atoms is weaker than the interaction between F and Mg.

Improving hot corrosion resistance of aluminized TiAl alloy by anodization and pre-oxidation

To shield TiAl alloy from hot corrosion attack,a compact protective coating was fabricated by the combination of aluminizing,anodization and pre-oxidation.The hot corrosion behavior of the coated-TiAl specimen was investigated in the mixture salt consisting of 75 wt.%Na2SO4 and 25 wt.%NaCl at 700°C.Results indicated that the anodization and pre-oxidation were beneficial to the generation of Al2O3 layer,which could act as a diffusion barrier to prevent the molten salts and oxygen from diffusing into the alloy during exposure to a hot corrosion environment while the aluminizing coating could provide sufficient aluminum source to support the continuous formation of Al2O3 layer.Moreover,the internal stress of the coating was reduced due to the formation of a gradient coating consisting of TiAl3 and TiAl2.

Corrosion behavior and electrochemical property of Q235A steel in treated water containing halide ions(F^-, Cl^-) from nonferrous industry

The corrosion behaviors and electrochemical properties of Q235 A steel in the treated water containing corrosive halide anions(F-, Cl-) have been investigated with corrosion tests of static coupon and dynamic coupon testing, electrochemical measurement of open-circuit potential and linear sweep voltammetry. The results reveal that the existence of F-and Cl-ions in the simulated treated water accelerate the corrosion rate of Q235 A steel. The corrosion rate reaches maximum with F-concentration of 50 mg/L, Cl-concentration of 200 mg/L, respectively. However, Q235 A steel would passivate when an applied potential is added to the system. Meanwhile, the initiating passive potential becomes positive with F-, Cl-concentration increasing. There is a little influence of F-, Cl-concentration on the initiating passivation current density. Therefore, it is necessary to control F-, Cl-concentration in the treated water when it is recycled by the pipelines made of Q235 A steel.

Accelerated Interfacial Charge Transfer in Br-Gradient MAPbI_(3-x)Br_(x) Perovskite Thin Films

Mixed halide perovskites(MHPs)are a class of semiconductor materials with great promise for many optoelectronic applications due to their outstanding photophysical properties.Understanding and tailoring the photogenerated carrier dynamics is essential for further improvement of perovskite performance.Herein,we report a study about the carrier transport and interfacial charge transfer dynamics in Br-gradient MAPbI_(3-x)Br_(x) perovskite thin films prepared by surface ion-exchange method.Driven by the bandgap gradient in MAPbI_(3-x)Br_(x) films,the accelerated internal hole transport and enhanced interfacial extraction efficiency were both observed.Meanwhile,the interfacial electron transfer was also found to be evidently facilitated due to the surface modification during post-treatment.Our findings suggest the possibility of simultaneous acceleration of interfacial electron and hole transfer processes in halide perovskite films via surface post-treatment technique,which is of great importance in further improving the power conversion efficiency of perovskite solar cells.

Synthesis of Some More New Fluorinated 1,2,4-triazino[3,4-b][1,3,4]Thiadiazolonesand Their Molluscicidal Against Selective Snails - Part I

Some more new fluorinated 1,2,4-triasino[3,4-b][1,3,4]thiadiazolones （6-9 and 11-16） have been synthesized from cyclocondensation of 5-hydrazino-2-（4＇-fluorophenyl）-1,3,4-thiadiazole with bifunctional oxygen and halogen compounds. Structures of the products have been deduced from their elemental, chemical and spectral data （UV, IIL 1H/13C NMR （nuclear magnetic resonance） and mass）. All the new compounds evaluated as molluscicidal against towards snails which responsible for Bilharziasis diseases.

Preliminary Theoretical Studies on the Combination of Halogen Ions with Crown Tetraalanylpeptide

The density functional theory based hybrid-method B3LYP was used to investigate the interaction of the halogen ions with crown tetraalanylpeptide which was the coronary structures of homodetic cyclotetraalapeptide and was represented as the model basic. Many properties including combination energy, optimum geometry structures and population analysis were calculated. It was shown that there was scarcely any change in the coronary structure of C4-Ala after combination with X. The electrons moved from halogen ions to C4-Ala during the combining process. Combination of C4-Ala with F was obviously stronger than that of Cl^- and Br. When the energy of C4-Ala-X was at minimum, the distances between halogen ions and the center of C4-Ala were 0.084 nm, 0.210 nm and 0.200 nm, respectively.