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化学学报
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化学学报 ›› 1989, Vol. 47 ›› Issue (11): 1071-1075. 上一篇    下一篇

研究论文

金属电极上的中和滴定法:II. 不同预处理对Pt电极 pH响应的影响

谢远武;高鸿   

  1. 南京大学化学系
  • 发布日期:1989-11-15

Neutralization titration with metal electrodes:II, The effect of different pretreatment of pH response of platinium electrode

XIE YUANWU;GAO HONG   

  • Published:1989-11-15

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本文讨论了不同的预处理对Pt电极 pH 响应的影响 。经阴极 极 化或火焰上红热后, Pt电极以Pt(OH)2+Ze-Pt+2OH响应溶液的pH。而经+1.5V(vs.SCE)阳极极化后, 由于Pt电极表面PtO2的快速分解,电极的电位值很快下降, 并逐渐达到稳定值, 稳定后的Pt电极仍以上式响应溶液的pH。用KMnO4溶液浸泡后, Pt电极表面有MnO~2沉积, 并以MnO2+4H^++Ze-Mn^2^++2H2O(PH2-7)ZMnO2+2H^++Ze-Mn2O3+H2O(PH8-12)响应溶液的pH。

关键词: 滴定, 氧化, 铂, 金属电极, 酸度, 中和, 高锰酸钾, 电极电位

For a Pt cathode, the following equation is given for the electrode processes: Pt(OH)2 + 2e- = Pt + 20H- or PtO + 2H+ + 2e- = Pt + H2O. After anodization in 0.1M H2SO4 at 1.5 V (vs. SCE), the Pt electrode is partially covered with PtO2. Under open-circuit conditions, PtO2 decomps. to PtO in the presence of Pt. The electrode potential decreases rapidly and gradually reaches a stable value. The stabilized Pt electrode also responds to pH according to the above-mentioned equation. After soaked in permanganate solution, the Pt electrode is covered with MnO2. The potential vs. pH behavior is close to that predicted for the following reactions: MnO2 + 4H+ + 2e- = Mn2+ + 2H2O (pH 2-7) or 2MnO2 + 2H+ + 2e- = Mn2O3 + H2O (pH 8-12).

Key words: TITRATION, OXIDATION, PLATINUM, METAL ELECTRODE, ACIDITY, NEUTRALIZATION, POTASSIUM PERMANGANATE, ELECTRODE POTENTIAL

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