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电导滴定法测定镍的含量 总被引:3,自引:0,他引:3
由电导滴定法确定终点,在氨性介质中用丁二酮肟乙醇溶液滴定镍的含量,采用硫脲掩蔽Cu(Ⅱ),用H2O2将Mn(Ⅱ),Co(Ⅱ)氧化成Mn(Ⅳ)和Co(Ⅲ)消除干扰,其它金属离子对测定没有干扰,此法的测定结果与丁二酮肟重量法接近,且不受溶液的颜色、浊度的影响,具有准确、快速、干扰少的特点,适用于化学镀镍溶液,电镀镍和镍合金中镍的测定。 相似文献
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The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory. 相似文献
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Quantitative Correlation of the Acute Toxicity of Phenylthio-carboxylates with Their Structural and Thermodynamic Parameters by DFT Calculation 总被引:1,自引:1,他引:0
1 INTRODUCTION As industrial raw materials and pesticide, thio-ether, sulfoxide and sulfone have been used moreand more extensively. On the other hand, they havealso attracted chemists’ much attention due to theirpotential environmental hazards. Quantitative struc-ture-activity relationship (QSAR) is an effective me-thod evaluating the hazards of organic chemicals[1].QSAR equation could be employed to forecast thebiological activity of unknown compounds, which issignificant for initia… 相似文献
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用密度泛函理论(DFT)B3LYP方法,取3-21G**基组研究了气相反应Br2+2HI=2HBr+I2的机理,求得一系列四中心和三中心的过渡态.双分子基元反应Br2+HI→HBr+IBr和IBr+HI→I2+HBr的活化能(81.02和121.08 kJ•mol-1)小于Br2、HI和IBr的解离能(249.21、320.16和232.42 kJ•mol-1),故从理论上证明了标题反应将优先以分子与分子作用形式分两步完成.同时发现I原子与Br2分子反应生成较稳定的IBr2是一个无能垒过程,IBr2分解为IBr和Br原子的能垒为70.88 kJ•mol-1. 相似文献
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二氨基二硝基乙烯结构和性质的理论研究 总被引:13,自引:0,他引:13
对三种二氨基二硝基乙烯同分异构体进行了HF/6-31G^*^*水平、DFT-B3LYP/6-31G^*^*水平的几何全优化以及MP2/6-31G^*^*//HF-6-31G^*^*水平的总能量计算。结果表明,1,1-二氨基-2,2-二硝基乙烯(Ⅰ)总能量比顺式(Ⅱ)和反式(Ⅲ)1,2-二氨基-1,2-二硝基乙烯的总能量低,即热力学稳定性次序为Ⅰ>Ⅲ>Ⅱ。分子的共轭性和分子内氢键的强度次序为Ⅰ≈Ⅲ>Ⅱ,前沿轨道能级差次序为Ⅰ>Ⅱ>Ⅲ,也均表明(Ⅰ)最稳定。此外还计算研究了标题物的红外光谱;化合物Ⅰ的理论计算与实验值良好相符。在此基础上计算研究了标题物的热力学性质。 相似文献
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Phthalate acid esters (PAEs) possess endocrine disruptive effects and can produce reproductive and developmental toxicities. In this paper, both experimental and theoretical studies on FT-IR, Raman and 1H NMR spectra of diethyl phthalate (DEP) have been carried out. The geometrical structure of DEP was optimized at the HF/6-31G*, HF/6-311G**, B3LYP/6-31G*, and B3LYP/6-311G** levels, respectively. The harmonic vibrational frequencies, IR intensity, Raman activity and 1H NMR chemical shifts have been computed at the B3LYP/6-31G* and B3LYP/6-311G** levels. Anharmonic corrections to frequencies were obtained by means of second-order perturbation theory (PT2) at the B3LYP/6-31G* level. Based on potential energy distribution (PED), the vibrational assignments have also been performed. The theoretical calculation values were compared with the experimental observations and the results indicate they are in excellent agreement. 相似文献