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改进了探究分子运动实验,操作简单,现象明显,不仅证明了氨水分子不断运动,而且可以证明酚酞分子也在不断运动,使学生更好地理解分子运动的普遍性规律。 相似文献
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M. Jiménez-Reyes M. Solache-Ríos A. Rojas-Hernández 《Journal of solution chemistry》2006,35(2):201-214
The specific ion interaction theory (SIT) was applied to the first hydrolysis constants of Eu(III) and solubility product
of Eu(OH)3 in aqueous 2, 3 and 4 mol⋅dm−3 NaClO4 at 303.0 K, under CO2-free conditions. Diagrams of pEuaq versus pCH were constructed from solubilities obtained by a radiometric method, the solubility product log10 Ksp, Eu(OH)3I {Eu(OH)3(s)
Euaq3++ 3OHaq− } values were calculated from these diagrams and the results obtained are log10 Ksp,Eu(OH)3I = − 22.65 ± 0.29, −23.32 ± 0.33 and −23.70 ± 0.35 for ionic strengths of 2, 3 and 4 mol⋅dm−3 NaClO4, respectively. First hydrolysis constants {Euaq3++H2O
Eu(OH)(aq)2++H+ } were also determined in these media by pH titration and the values found are log10βEu,HI = − 8.19 ± 0.15, −7.90 ± 0.7 and −7.61 ± 0.01 for ionic strengths of 2, 3, and 4 mol⋅dm−3 NaClO4, respectively. Total solubilities were estimated taking into account the formation of both Eu3+ and Eu(OH)2+ (7.7 < pCH < 9) and the values found are: 1.4 × 10−6 mol⋅dm−3, 1.2 × 10−6 mol⋅dm−3 and 1.3 × 10−6 mol⋅dm−3, for ionic strengths of 2, 3 and 4 mol⋅dm−3 NaClO4, respectively. The limiting values at zero ionic strength were extrapolated by means of the SIT from the experimental results
of the present research together with some other published values. The results obtained are log10 Ksp, Eu(OH)3o = − 23.94 ± 0.51 (1.96 SD) and log10βEu,H0 = − 7.49 ± 0.15 (1.96 SD). 相似文献
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本文以Igepalco-880-2TPB为电活性物质,研制了中性载体PVC膜铅离子选择性电极;以邻硝基二苯醚和邻硝基十二烷基醚为介体溶剂,测定了电极对一些常见的一价和二价离子的选择系数,除钡离子外,均在10-3-10-5数量级;适用的pN范围为2-5,电极的重现性、稳定性均较好。 相似文献
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Anodic deposition of iodide ion on silver at 25° in aqueous (0.5 M KNO3) and in 90% (w/w) ethanol-water (0.05 M KClO4) solutions was studied galvanostatically. The exchange current density, transfer coefficient and the rate constants for the electrode reaction were evaluated. The experimental results revealed that the overall electrode reaction and the charge-transfer step was the same one, i.e., , which might be assumed highly reversible as reflected by the exchange current density (i) and transfer coefficient (α). The numerical values of the rate constants, and at 25° were, in aqueous solution, 1.02×10?5 and 2.88×10?6, and in ethanol solution, 2.88×10?5 and 6.3×10?6 cm sec?1, respectively. 相似文献
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新型杯芳烃为载体的铅离子选择电极 总被引:2,自引:0,他引:2
报道了5,11,17,23-四(1,1-二甲基乙基)-25,27-二羟基-26,28-二[(2-丙酰胺)乙氧基]杯[4]芳烃1的合成及以此化合物为载体研制了PVC膜铅离子选择电极。研究了不同极性的膜增塑剂和亲脂性阴离子位点对铅离子选择电极响应性能的影响,测定了铅离子选择电极的性能。铅离子选择电极对铅离子表现出优良的能斯特响应和高选择性,能在pH4.0-6.5的范围内使用,该电极可作为电位滴定的指示电极。 相似文献
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运用溶度积计算出与氢氧化镁沉淀相关的反应、与硫化铜沉淀相关的反应、与碳酸钙沉淀相关的反应的平衡常数。通过以上的计算与分析,让学生熟练掌握了运用溶度积计算化学平衡常数,从而判断反应能否发生。 相似文献
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《Analytical letters》2012,45(10):629-640
Abstract A perchlorate ion selective electrode of the liquid ion exchanger membrane type is shown to respond selectively to perchlorate ion acetivity over the 10?1 to 10?3.5 M range in aqueous solutions of pH 4 to 11. The electrode is of some analytical usefulness because of its good selectivity for C10? 4 over common univalent anions and is employed, herjft, for the determination of solubility product constants of potassium perchlorate, hexamminecobaltiperchlorate, tetrapyridine cupric perchlorate, and tris-1, 10-phenanthroline ferrous perchlorate. 相似文献
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研制了盐酸氟桂嗪离子选择性电极。利用正交设计法综合研究了活性的类型、含量以及增塑剂等因素对PVC膜电极响应性能的影响,结果表明,以盐酸氟桂嗪-四苯硼钠离子缔合物为活性物质,DBP或DOP为增塑剂制成的PVC膜电极的性能最佳。其响应范围为1.0×10^-4-5.0×10^-3mol/L,检测下限为3.5×10^5mol/L,响应斜率为58mV(25℃)。应用该电极对合成样品及胶囊样品中盐酸氟桂嗪含量 相似文献
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1引言研制中性载体PVC膜离子选择电极,关键是设计及选择合适的载体。杯芳烃衍生物作为高选择性载体已成功地用于离子选择电极上。本研究合成了两种新的对-叔丁基杯[4]芳烃磷酸酯类衍生物,以此化合物为载体制备了两种铅离子选择性膜电极,并对电极的性能进行了研究。2实验部分2.1 相似文献
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A novel membrane sensor for selective monitoring of iodide, consisting of a triiodide‐ketoconazole ion pair complex dispersed in a PVC matrix, plasticized with a mixture of 2‐nitrophenyl octyl ether and dioctylphtalate with unique selectivity toward iodide ions, is described. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The optimized membrane demonstrates a near‐Nernstian response for iodide ions over a wide linear range from 1.0 × 10?2 to 1.0 × 10?5 M, at 25 ± 1 °C. The electrode could be used over a wide pH range 3–10 and has the advantages of high selectivity, fast response time and good lifetime (over 4 months). It was successfully used as indicator electrode in potentiometric titrations and direct potentiometric assay of iodide ions. 相似文献
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钟爱国 《理化检验(化学分册)》2003,39(1):59-60
测定曲马多含量的常规方法为药典法[1] 。但其前处理手段繁琐费时 ;近来有关测定曲马多的选择性电极已有报道[2 ] ,但未见有关浸涂聚氯乙烯膜曲马多药物电极的报道。作者利用曲马多的碘化物与碘化铋形成的分子型缔合物为电活性物质 ,研制出盐酸曲马多 聚氯乙烯液膜涂层的玻璃电极。此药物电极制作方便 ,再生容易 ,响应迅速 ,在 pH 3.5~ 7.0范围对曲马多有良好的电位响应。1 试验部分1.1 主要仪器与试剂pHS 3C型精密酸度计 ;PXD 12型数字式离子计 ;2 31型玻璃电极。盐酸曲马多 (纯度为 99.90 % ,康乐制药厂提供 ) ;盐酸曲马多注… 相似文献
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The mixture of silver iodide and ferrocene is used to prepare the membrane of iodide ion-selective electrode. The interference of sulfide can be reduced by the addition of cupric ion in the test solution. Ethylene glycol is determined by potentiometric titration using iodine ion-selective electrode as an indicator electrode. 相似文献
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利用溶度积常数从理论上判断BaSO4沉淀转化成BaCO3沉淀的问题,然后用实验进行了验证。表明理论联系实践,实验检验理论是加深理解理论的重要方法。从而启发教师在上实验课时要把实验中可能出现的问题先交给学生,使学生由被动变为主动,提高学生分析问题和解决问题的能力。 相似文献