Equilibrium in the System: Arsenic Pentoxide, Barium Oxide, Water
Equilibrium in the System: Arsenic Pentoxide, Barium Oxide, Water
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系统平衡：五氧化二砷、氧化钡、水
DOI：
10.1021/j150260a006
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通讯作者：
S. Hendricks
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作者：
S. Hendricks
越来越多地使用碱性砷酸盐作为杀虫剂，这就需要对这些物质的化学性质有更全面的了解。接下来的研究描述了BaO，As205，H20体系酸段的研究结果。由于在碱性溶液中不能迅速建立平衡条件，因此该体系的基本部分将在稍后报告。材料的制备。-Ba(OH)2.8H20是从无CO_2的蒸馏水中重结晶“CP”试剂制备的。对Cu、CoF-、N03~的检测均为阴性。AS206。QH20由C.M.Smith*1.实验程序-100cc所述的方法制备。实验容器采用石蜡软木塞油样瓶。将已知浓度的含有部分固相的溶液放入其中，然后将其放入恒温器中，恒温器调节为30o±i，通过每隔一周分析溶液来确定平衡条件。分析是以下面给出的方式进行的。分析-用比重瓶测定溶液的密度，温度为20℃。用硫酸盐法测定钡，点燃的BaS04用锥体润湿。硫化氢，并重新点燃，以去除氯杂质。用锥体滴定从碘化物中析出的I2来测定砷。HCl溶液，使用的是准确标准化的Na2S203溶液。由于任何对固相进行干燥或洗涤的尝试都可能导致水解或脱水，因此有必要使用湿沉淀物的分析方法2来确定固相的组成。由于分析中存在微小的实验误差，决定固相组成的几条直线的确切交点不能用图解的方法确定。几条直线的最可能的交点被认为是与直线垂直距离的平方和最小的点。由于在酸性较强的溶液中，确定一条线的两个点非常接近，因此有必要通过显微镜手段来鉴定存在的固相。分析结果见第250-251页。
The increasing use of alkaline arsenates as insecticides necessitates a more complete knowledge of the chemical properties of these substances. The fol-lowing research describes the results obtained from a study of theacid section of the system BaO, As205, H20. Since equilibrium conditions are not rapidly established in basic solutions the basic section of this system will be reported later.Preparation of Materials.—Ba (OH) 2. 8H20 was prepared by recrystallizing “CP” reagent from C02—free distilled water. It gave a negative test for CU, COf-, and N03~. As206. qH20 was prepared by the method previously described by C. M. Smith* 1. Experimental Procedure.—ioo cc. paraffined cork stoppered oil sample bottles were used for experimental vessels. Solutions of known concentration, containing some of the solid phase, were placed in these and were then im-mersed in a thermostat regulated at 30o±, i. Equilibrium conditions were determined by analysis of the solutions at intervals of one week. Analyses were made in the manner given below. Analysis.—The densitiesof thesolution were determined by means of a pycnometer, the temperature being 20. The barium was determined by the sulfate method, the ignited BaS04 being moistened with cone. H2S04 and reignited in order to remove chloride impurities. The arsenic was determined by titrating the I2 liberated from an iodide in cone. HC1 solution, accurately standardized Na2S203 solution being used. Since any attempt to dry or wash the solid phase would probably have resulted in hydrolysis or dehydration, it was necessary to use the method of analysis of wet precipitates2 in order to determine the compositions of the solid phases. Since there were slight experimental errors involved in the analysis, the exact point of intersection of several lines determining the compo-sition of a solid phase could not be determined by graphical means. The most probable point of intersection of several lines was assumed to be that point at which the sum of the squares of the perpendicular distances to the lines was a minimum. Since the two points determining a line were very close together in the case of the more acid solutions, it was necessary to identify the solid phases present by microscopic means. The results of the analyses are given on pages 250-251.