Abstract

The results of studying the effect of solution pH on the electrode process that occurs on the gold electrode in solutions of sodium sulfite, sulfuric acid, and alkali, and also in the universal buffer of Britton–Robinson (pH 2–14) are shown. In sodium sulfite solutions, this electrode process represents a combination of the oxidation of sulfite species and the formation of oxides on the gold surface that proceeds simultaneously in the same potential region. It is shown that the solution pH and the oxidation of sulfite species have no effect on the amount of gold α-oxide formed. At the same time, the solution pH has a strong effect on the oxidation of sulfite species. Thus, the voltammograms measured in solutions with pH approximately between 2 and 11 are identical, i.e., the process rate is independent of the solution acidity and its partial composition. These results suggest that in this pH region, the oxidation of sulfite ions can be interpreted by the overall reaction \(2{\text{SO}}_{3}^{{2 - }} \to {{{\text{S}}}_{{\text{2}}}}{\text{O}}_{6}^{{2 - }} + 2{\text{e}}\) to produce dithionate ions. In strongly alkaline solutions (pH 12.5–14), the oxidation potential shifts in the negative direction and the current decreases with increasing pH. These results suggest that in strongly alkaline solutions, the oxidation of sulfite ions can proceed on the partly blocked electrode surface by the reaction \({\text{SO}}_{3}^{{2 - }} + 2{\text{O}}{{{\text{H}}}^{ - }} \to {\text{SO}}_{4}^{{2 - }} + {{{\text{H}}}_{{\text{2}}}}{\text{O}} + 2{\text{e}}\) to form sulfate ions. The changeover of the mechanism of oxidation of sulfite ions takes place in a narrow potential region in solutions with pH from 11 to 12.5 and is accompanied by anomalously sharp changes in the measured current. The latter anomalies are associated with the peculiar dynamics of the process of passivation/depassivation of the electrode surface by gold oxides.

中文翻译：

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溶液pH值对亚硫酸根离子氧化和金电极上氧化物形成的影响。

摘要

显示了研究溶液pH对在亚硫酸钠，硫酸和碱溶液以及Britton-Robinson通用缓冲液（pH 2-14）中金电极上发生的电极过程的影响的结果。在亚硫酸钠溶液中，此电极过程代表了亚硫酸盐物种的氧化与在同一电位区域中同时进行的金表面氧化物的形成的结合。结果表明，溶液的pH值和亚硫酸盐物种的氧化对形成的金α-氧化物的量没有影响。同时，溶液的pH值对亚硫酸盐物种的氧化有很大影响。因此，在pH值约为2到11之间的溶液中测得的伏安图是相同的，即 处理速度与溶液的酸度及其部分组成无关。这些结果表明，在此pH范围内，亚硫酸根离子的氧化可通过整个反应来解释。\（2 {\ text {SO}} _ {3} ^ {{2-}} \ to {{{\ text {S}}} _ {{\ text {2}}}} {\ text {O} } _ {6} ^ {{2-}} + 2 {\ text {e}} \}生成二硫代离子。在强碱性溶液（pH 12.5–14）中，氧化电位朝负方向移动，电流随pH值的增加而减小。这些结果表明，在强碱性溶液中，亚硫酸根离子的氧化可通过\（{\ text {SO}} _ {3} ^ {{2-}} + 2 {\ text {O}} {{{\ text {H}}} ^ {-}} \ to {\ text {SO}} _ {4} ^ {{2-}} + {{{\ text {H}}} _ {{\ text {2}}}} {\ text {O}} + 2 {\ text {e}} \）形成硫酸根离子 亚硫酸根离子的氧化机理的转变发生在pH值为11至12.5的溶液中的狭窄电位区域中，并伴随着测量电流的异常急剧变化。后者的异常与氧化金对电极表面的钝化/去钝化过程的特殊动力学有关。