瓦耳登還原器

瓦爾登還原器（Walden reductor）是一種銀還原柱，它能將水溶液中的金屬離子還原成較低價的氧化態。例如:將UO₂²⁺還原成U⁴⁺，^[1]此還原柱由喬治.H.瓦爾登（George H. Walden）與他的博士生賽文.M.愛德蒙斯（Sylvan M. Edmonds）於哥倫比亞大學共同研發。^[2]

製備及使用

將一段銅線浸在硝酸銀溶液中，金屬銀迅速在銅線上形成樹枝狀結晶析出：

Cu + 2Ag⁺ —> Cu²⁺ + 2Ag

然後把銀結晶從銅線上取下，並用純水沖洗除去多餘的硝酸銅和硝酸銀後放進一細小的玻璃管柱中。^[2]^[3]
這個裝置類似柱層析，使用時，將欲還原的金屬離子水溶液從頂端倒入，使其順着管柱自然流下，還原反應隨之進行，溶液到達管柱下端時，還原反應接近100%完成。^[2]^[3]

應用

此方法可以用來在化學分析時獲得較低價態的化學物質，或者製備少量化合物。^[1]^[2]^[3]

參見

其他還原器

瓊斯還原器

其他氧化劑

參考資料

^ ^1.0 ^1.1 Mendham, J; Denney, R.C; Barnes, J.D.; Thomas, M. (2000). Vogel's Textbook of Quantitative Chemical Analysis (6th ed.). Pearson Education Ltd. ISBN 0-582-22628-7.
^ ^2.0 ^2.1 ^2.2 ^2.3 Walden, George H.; Hammett, Louis P.; Edmonds, Sylvan M. (1934). "Phenathroline-Ferrous Ion. III. A Silver Reductor. The Direct Determination of Iron in the Presence of Vanadium". Journal of the American Chemical Society 56 (2): 350. doi:10.1021/ja01317a023
^ ^3.0 ^3.1 ^3.2 Smith, G. F.; Cagle, F. W. (1948). "Preparation of Silver for Use in Walden Silver Reductor". Analytical Chemistry 20 (2): 183. doi:10.1021/ac60014a024

進一步閱讀

Birnbaum, Nathan; Edmonds, Sylvan M. New applications of the silver reductor. Industrial & Engineering Chemistry Analytical Edition. 1940, 12 (3): 155–157. ISSN 0096-4484. doi:10.1021/ac50143a013.
Edmonds, Sylvan M.; Birnbaum, Nathan. Microdetermination of iron with the silver reductor. Industrial & Engineering Chemistry Analytical Edition. 1940, 12 (1): 60–61. ISSN 0096-4484. doi:10.1021/ac50141a024.
Huffman, Eugene H. Regeneration of Walden silver reductor. Industrial & Engineering Chemistry Analytical Edition. 1946, 18 (4): 278. doi:10.1021/i560152a023.
Khan, M.A. Salam; Stephen, W.I. An improved silver reagent for use in the Walden silver reductor. The Analyst. 1968, 93 (1102): 26. Bibcode:1968Ana....93...26K. ISSN 0003-2654. doi:10.1039/an9689300026.
Pantani, Francesco. The use of the silver reductor in bromide solutions. Analytica Chimica Acta. 1964, 31: 121. doi:10.1016/S0003-2670(00)88792-9.

[one-1] 1.0 ^1.1 Mendham, J; Denney, R.C; Barnes, J.D.; Thomas, M. (2000). Vogel's Textbook of Quantitative Chemical Analysis (6th ed.). Pearson Education Ltd. ISBN 0-582-22628-7.

[two-2] 2.0 ^2.1 ^2.2 ^2.3 Walden, George H.; Hammett, Louis P.; Edmonds, Sylvan M. (1934). "Phenathroline-Ferrous Ion. III. A Silver Reductor. The Direct Determination of Iron in the Presence of Vanadium". Journal of the American Chemical Society 56 (2): 350. doi:10.1021/ja01317a023

[three-3] 3.0 ^3.1 ^3.2 Smith, G. F.; Cagle, F. W. (1948). "Preparation of Silver for Use in Walden Silver Reductor". Analytical Chemistry 20 (2): 183. doi:10.1021/ac60014a024

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