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仲钨酸A和仲钨酸B都是z(H~+/W)=1.14的两种钨同多酸,前者在WO_4~(2-)酸化至z=1.14时能快速形成,后者需要WO_4~(2-)酸化后经过长时间的加热方能定量完成。以往,由于它的转变速度极其缓慢,加之缺乏可靠的分离和鉴定方法,使仲钨酸A转变成仲钨酸B这一反应的动力学研究存在一定的困难,因而文献上报道的机理是主观的推测,缺少实验的依据。 作者利用仲钨酸A对H_2O_2有络合活性而仲钨酸B无络合活性这一性质差异,成功地找到了仲钨酸B的测定方法,从而使仲钨酸A转变成仲钨酸B的动力学研究成为可能。本文根据得到的动力学研究结果,提出新的有实验依据的转变机理。
Both paratungstate A and paratungstate B are two tungsten isopolyacids with z (H ~ + / W) = 1.14 which rapidly forms when WO_4 ~ (2-) is acidified to z = 1.14, the latter requiring WO_4 ~ (2-) acidification after a long period of heating can be done quantitatively. In the past, due to its extremely slow transformation speed and the lack of reliable separation and identification methods, the kinetics of the conversion of paratungstic acid A to paratungstic acid B has some difficulties. Therefore, the mechanism reported in the literature is subjective Speculation, the lack of experimental basis. The author has successfully found the determination of paratungstic acid B by using the property that para-tungstic acid A has a complexing activity on H 2 O 2 and non-complexing activity of paratungstate B, so that para-tungstic acid A is converted into para-tungstic acid B Kinetic studies possible. Based on the kinetic results obtained, this paper proposes a new experimental mechanism of transformation.